I am using

http://www.ragepank.com/redirect-check/

to check my site: http://www.trade-th.com

to check my redirects, when I found these Internal Server Errors

http://www.trade-th.com/default.aspx returns a HTTP/1.1 500 Internal Server Error response
http://trade-th.com/default.aspx returns a HTTP/1.1 500 Internal Server Error response
http://www.trade-th.com/index.aspx returns a HTTP/1.1 500 Internal Server Error response
http://trade-th.com/index.aspx returns a HTTP/1.1 500 Internal Server Error response

could someone help me to correct or redirect these ?

I tried adding this to the .htaccess

RewriteEngine on
Options +FollowSymLinks
RewriteCond %{THE_REQUEST} ^.*/default\.aspx
RewriteRule ^(.*)default.aspx$ http://www.trade-th.com/$1 [R=301,L] RewriteCond %{THE_REQUEST} ^.*/index\.aspx
RewriteRule ^(.*)index.aspx$ http://www.trade-th.com/$1 [R=301,L]

but it did not help

all help greatly appreciated