When I debug, it shows executing the routine, but the ddl's selected index is always zero, no matter which item I select.

It didn't always do this. Earlier, it would work correctly for one dataSource, but not another (yes, I use a different data source, depending on who logs on).

So I removed the selectedIndexChanged module, cleaned the solution, built the solution, removed the .dll and .pdb, recompiled, re-added the module (including by double clicking the control), recompiled.... but now neither data source works.

I found the problem, though I'm not sure why it happens.

It turns out that 2 databinds were executed on the ddl before I would select an item. Then it wouldn't reflect any selection for some reason. Tjis happened for both datasources.