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.
the Telerik team