I'm trying to use the CascadingDropDown control, but I am recieving an error. I have no problem filling my two dropdownlist with the proper data, but when I try and grab the values using a button. I get this error.
Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
What am I doing wrong?