我试图从下拉菜单中拉出sql数据源的控制参数，但它没有被识别

I have 2 sql datasources. What's supposed to happen is the following: On page load, the first sql datasource pulls a list of 'desknames' and populates a dropdown. It should default to the first deskname but I added some c# code behind to select the first item by index on pageload just to be safe. Then a second sql datasource should load, using the selected 'deskname' as a control parameter. From the second sql datasource I populate an html table with labels that are populated in the code behind from the datasource. I've tested the second datasource-html table when I manually put in the control parameter, and it works fine.I have 2 sql datasources. What's supposed to ha