You might want to try turning off custom errors in the web.config file in case an error is occurring and you are being redirected to error.aspx or possibly error404.aspx. You would want to change the mode to Off (it's case sensitive):
<customErrors mode="Off" ..... />
This may or may not help. If it does help, then you'll probably see some error details rather than getting "Post Not Found" -- but not sure entirely.