User Control won't show on server but does on development machine

I was having trouble getting a div and panel to appear when published code was put on a server, but would appear on my local development PC.  So I decided to change the div/panel to a user control as other user controls were not having this issue.  Turns out, I have the same issue with the user control.  It will pop up on my local development machine when I run the code, but then when I compile and put the code out on the server it doesn't show up. 
I updated my web application from .NET Framework 2.0 to 4.0.  The div/panel worked in the previous Framework version (2.0).
Any ideas on why this would work locally but not on a server?  This is an intranet site.  On my local machine, I can succesfully run the web application in Google Chrome, Firefox, and IE.  When I try to do the same on machines hitting the server where the compiled code is, none of these browsers will bring up the user control.&nbs ...