Void firing before changes

I've got an asp.net page with a void that I run whenever one of two dropdowns chages. It does some counting and sets the datasource of a gridview for me. It's doing what I want...almost.

The problem is I've got some parameters which I attempt to set before I call it (UserName, Start and End Date). But, they don't actually change until after it runs. That happens on page_load and in any postbacks.   "On paper" my parameters are changed first. Bottom line, my counts and gridview appear to be one step behind.

I can get something almost right setting the void to run on an selected value changes in the two dropdowns, but my load event doesn't work that way.