Hi Carl,

I'm guessing that you are seeing multiple postbacks because the SELECT is losing focus several times as the debugger takes focus away, and gives it back -- the extender fires the OnChange when the SELECT loses focus.

With regards to the error with the CascadingDropDownExtender, I have not managed to reproduce this -- I added ListSearchExtenders to each of the lists on the CascadingDropDown example in the toolkit and had no issues -- could you perhaps post a small example where you are getting an error?

Thanks,

Damian