Need Help with Registration Capcha

[vampireduff]

I have been told that when players try to sign up to my site (game) the Capcha keeps failing and wont let them sign up.

so I tried with a test account and as soon as I entered my details and the Capcha and clicked on the submit I got the message 'Capcha test failed'.

I thought it may have something to do with the Register.php file so I changed it 6 times (each file coming from different people) but again each time I try to register with the test account the same message pops up. could anyone tell me what file could be at fault so I could try to fix it. Or if anyone has had this prob could you please tell me how you fixed it. Thanks