I have three dropdownlists in an AJAX UpdatePanel and I need to return the
selected index for two of them; the problem is that I'm only able to return
the selected index for the first dropdownlist of the three and it is the one
that I don't need.  The dropdownlists are named, in order, ddlEntityType,
ddlEntityGroups and ddlProcesses.  The Javascript for attempting to read the
selected index is as follows:

   var entityTypeIndex =
document.getElementById('ct100$ContentPlaceHolder1$ddlEntityType').selectedIndex;        // this one works
   var entityGroupIndex =
document.getElementById('ct100$ContentPlaceHolder1$ddlEntityGroups').selectedIndex;     // this doesn't work
   var processesIndex =
document.getElementById('ct100$ContentPlaceHolder1$ddlProcesses').selectedIndex;        // this doesn't work

Trying all three in the Immediate Window, the first one still works; the
message I get back for the other two is:  Object required

Why won't it find the dropdownlists for the two that I need to return the
SelectedIndex from?