Are you trying to achieve something close to the scenario we have in our Related DropDownLists
demo, where the DropDownList controls are bound to one database and the selection in one of them affects the items displayed in the other?
Please, review the code of the demo, note that the AutoPostBack
property of the first and second DropDownLists is set to "true".
In case it doesn't help you find and fix the problem in your code, I am attaching the demo isolated as a sample project, so you can try to reproduce the issue in it and post your modifications.