I am trying to execute a stored procedure through .NET but the stored procedure doesn't seem to work. I know that my code in .NET works without any errors and I am almost sure my stored procedure code is correct but it is not executing what I want it to do.

In the code if I want to change the date in the drop down box and then hit the Save button it should execute the stored procedure in the Save button click event to update the record in the database. Here is the code for the Save button:
Code:
 Protected Sub SaveButton_Click(ByVal sender As Object, ByVal e As System.EventArgs)
        ' Using onyxConnection
        Try
            dim @iReturnCode
            Dim cmd As New SqlCommand
            onyxConnection.Open()
            cmd.Connection = onyxConnection
            cmd.CommandType = CommandType.StoredProcedure
            cmd.CommandText = "cnpcuStudentSessionDate"
            cmd.Parameters.AddWithValue("@iProductId", lblProductID.Text)
            cmd.Parameters.AddWithValue("@chUserId", lblUpdateBy.Text)
            cmd.Parameters.AddWithValue("@dtPurchaseDate", ddlSession.SelectedValue)
            cmd.Parameters.AddWithValue("@dtSchEnrDate", ddlSession.SelectedValue)
            'cmd.Parameters.AddWithValue("@iProductId", txtAppProjNum.Text)
            'cmd.Parameters.AddWithValue("@iProductId", txtAppProjNum.Text)

            cmd.ExecuteNonQuery()

        Catch ex As Exception
            Dim a, b
            a = ex.ToString
            b = a.ToString

        Finally
        End Try

    End Sub

In the stored procedure I am selecting an existing record from the database and updating it with a new date. Here is the code for the stored procedure:

Code:
   
use DB
if exists  (select * from sysobjects
            where name = 'cnpcuStudentSessionDate' and type = 'P')
    drop proc cnpcuStudentSessionDate
go
create procedure cnpcuStudentSessionDate
        @iProductId    int,
        @chUserId   nchar(10),
		@dtPurchaseDate  datetime,
		@dtSchEnrDate datetime,
        @iReturnCode      int   = Null output
      
With Encryption

as



set nocount on

/* declare variables */
declare @dtNow datetime
/*           M003D Begin*/
declare @iIndividualId int,
		@dtReceivedDate datetime,
        @dtEnrollmentDate datetime,
        @vchScheduleNumber varchar(255),
        @vchCreditScore smallint,
        @siGuidesRequired smallint,
        @dcDeposit decimal(9, 2),
        @dcPendingDeposit decimal(9, 2),
        @dcDiscount decimal(9, 2),
        @dcShareDeposit decimal(9, 2),
        @dcNetAdjustment decimal(9, 2),
        @siTerm smallint,
        @dcPaymentAmount decimal(9, 2),
        @dtFirstDue datetime,
        @dtNextDue datetime,
        @dcInterestRate decimal(8, 5),
        @dcGrossSale decimal(9, 2),
        @dcInterest decimal(9, 2),
        @dcContract decimal(9, 2),
        @dcCurrentBalance decimal(9, 2),
        @dcContractPaid decimal(9, 2),
        @dcInterestPaid decimal(9, 2),
        @dcAccruedInterestBalance decimal(9, 2),
        @dcInterestPerDiem decimal(9, 2),
        @dcEstimatedPayoff decimal(9, 2),
        @siTotalPayments decimal(9, 2),
        @dcTotalPaid decimal(9, 2),
        @dtDisbursementDate datetime,
        @dcChargeOff decimal(9, 2),
        @dcInvoiceBalance decimal(9, 2),
        @dtInvoiceDate datetime,
        @iInvoiceStatus int,
        @dcAdjDiscount decimal(9, 2),
        
        @dcSalesTax decimal(9, 2),
        @dcPendingSalesTax decimal(9, 2),
        @iOwnerId int,
        @dcFinancedSalesTax  decimal(9,2)       --M001A
                /*M003D End */
                --M003A Begin
declare @iSiteId int,
    @chLanguageCode     nchar(4),
    @iContactId         int,
    @chProductNumber    nchar(20),
    @vchSerialNumber    nvarchar(50),
    @flQuantity         onyxfloat,    
    @iTrackingId        int,
    @iSourceId          int,
    @iStatusId          int,
    @iAccessCode        int,
    @vchUser1           nvarchar(30),
    @vchUser2           nvarchar(30),
    @vchUser3           nvarchar(30),
    @vchUser4           nvarchar(30),
    @vchUser5           nvarchar(30),
    @vchUser6           nvarchar(30),
    @vchUser7           nvarchar(30),
    @vchUser8           nvarchar(30),
    @vchUser9           nvarchar(30),
    @vchUser10          nvarchar(30),
    @dtUpdateDate       datetime

--Variables needed for incident Update.
declare
    @iIncidentId int,
	@tiLCMSAccount tinyint,
    @iIncidentCategory int,
    @iIncidentTypeId int,
    @vchAssignedId              nvarchar(255),
    @vchProductId nvarchar(255),
    @vchDesc1 nvarchar(255),
    @vchDesc2 nvarchar(255),
    @vchKeyWords nvarchar(255),
    @iPriorityId int,
    @iCode1 int,
    @iCode2 int,
    @iCode3 int,
    @iCode4 int,
    @iTime int,
    @iLabor int,
    @tiImage tinyint,
    @chAssignedTo nchar(10),
    @chInsertBy nchar(10),
    @dtInsertDate datetime,
    @tiRecordStatus tinyint,
    @iReminderId int
--M003A End

/* initialize variables */
set @dtNow = getdate()

/* set default values */

set          @iReturnCode  = 0



if isnull(@iProductId,0) > 0 and  isnull(@vchUser7,0) > 0
		begin
			--Get the current values of the customer product record.
			SELECT
				@chLanguageCode = [chLanguageCode]
				,@iContactId = [iContactId]
				,@chProductNumber = [chProductNumber]
				,@vchSerialNumber = [vchSerialNumber]
				,@flQuantity = [flQuantity]
				,@dtPurchaseDate = [dtPurchaseDate]
				,@iTrackingId = [iTrackingId]
				,@iSourceId = [iSourceId]
				,@iStatusId = [iStatusId]
				,@iAccessCode = [iAccessCode]
				,@vchUser1 = [vchUser1]
				,@vchUser2 = [vchUser2]
				,@vchUser3 = [vchUser3]
				,@vchUser4 = [vchUser4]
				,@vchUser5 = [vchUser5]
				,@vchUser6 = [vchUser6]
				,@vchUser7 = [vchUser7]
				,@vchUser8 = [vchUser8]
				,@vchUser9 = [vchUser9]
				,@vchUser10 = [vchUser10]
				,@dtUpdateDate = [dtUpdateDate]
			FROM [OnyxTCN].[dbo].[CustomerProduct]
			WHERE [iProductId] = @iProductId
 
			--If we have successfully registered this course in the LMS, proceed.
			if @tiLCMSAccount = 1
			begin
				--Set the tracking ID for the product to the Course Registered tracking id.
				--Sandbox: 5465		Live: 7743
				Set @iTrackingId = 7743
			end
			else
			begin
				--Set the tracking id for the product to the Course Not Registered tracking id.
				--Sandbox: 5474		Live: 7771
				Set @iTrackingId = 7771
			end
			if (select iTrackingId from customerProduct with (nolock) where iProductId = @iProductId) <> @iTrackingId
			begin
				--Update the customer product table.

				exec @iReturnCode = wbospsuCustomerProduct
					@iSiteId,			--iSiteId
					@iProductId,		--iProductId
					@iIndividualId,		--iOwnerId
					@chLanguageCode,	--Language Code
					@iContactId,		--Contact ID
					@chProductNumber,	--Product Number
					@vchSerialNumber,	--Serial NUmber
					@flQuantity,		--Quantity
					@dtPurchaseDate,	--Purchase Date
					@iTrackingId,		--Tracking Id
					@iSourceId,			--Source Id
					@iStatusId,			--Status Id
					@iAccessCode,		--Access Code
					@vchUser1,			--UDF1
					@vchUser2,			--UDF2
					@vchUser3,			--UDF3
					@vchUser4,			--UDF4
					@vchUser5,			--UDF5
					@vchUser6,			--UDF6
					@vchUser7,			--UDF7
					@vchUser8,			--UDF8
					@vchUser9,			--UDF9
					@vchUser10,			--UDF10
					@chUserId,			--chUpdateBy
					@dtUpdateDate,		--dtUpdateDate
					null,				--tiRecordUnlock
					null				--tireturnType
			end 
 return @iReturnCode
end
go

grant execute on cnpcuStudentSessionDate to public
go