I am using telerik captcha in .20 application configured in IIS 7.5. I have used the telerik dll which resides in .net bin 3.5 folder. Problem which I am facing is I am entering the exact value of captcha image in textbox but then also it is not authenticating the captcha. This problem does not exists on my local machine. Also when I am using this in .40 application it is working fine.