I'm getting unexpected results when using TABLESAMPLE in Microsoft SQL Server 2005 Express.

Both of the following SQL statements do not yield the results you would expect:

Code:
SELECT * FROM products
TABLESAMPLE (3 ROWS);
Code:
SELECT * FROM products
TABLESAMPLE (50 PERCENT);
I've also tried varying number and percentage values; all of which either yield nothing (just the column names), or all 14 rows of this table.

Please can somebody help?