Hi Gaurav,
Please follow these suggestions in order to achieve the desired functionality:
1. The property
ValidationGroup of the RadCaptcha and the button, that triggers postback, should have the same value.
2. The
ValidatedTextBoxID property of RadCaptcha should be set to the ID of the TextBox which you want to be validated. This is demonstrated in the following online demo:
http://demos.telerik.com/aspnet-ajax/captcha/examples/refreshimage/defaultcs.aspx.
3. In the button's click event handler, you can use the
IsValid property of RadCapthca to validate the input for the captcha. In
this online demo you can check a scenario, in which the IsValid property is used.
I would also suggest the
Getting Started help article, which contains useful information on utilizing the RadCapthca control.
You can find attached a sample page, implementing the desired functionality. Please use it as a base for your further development.
Kind regards,
Slav
the Telerik team