ModalPopup bad working with dropdownlist and postback

Try moving OkButton/CancelButton outside the UpdatePanel (but keep them inside the Panel).

Thank you for reply

Ok, now Ok and Cancel buttons seem to work...but remain the first problem:

i don't understand because the dropdownlist are populated very very slow in cascade when I change a value...

The Ok and CANCEL buttons close the window, but when I click ok button don't run the onclick event and don't run my onclick function. Why?

Perhaps I would have to use a cascading drop down control?

Thank you.

OK button above doesn't seem to have any "onclick" handling associated with it?

Regarding the slow population, you might see if the web service being called is responding slowly (or is slow to connect to). The CascadingDropDown population code itself isn't very involved, so the delays seem more likely to be due to the call to the method.