Why isn't my mouse-pad working?

I had to disassemble my Dell Inspiron N5010 laptop recently in order to clean out the cooling fan. I've done it before without incident, but this time around when everything was put back together and I turned it on, my mouse-pad (along with it's right and left click buttons) were not working. I know this is extremely specific, but does anyone know what connection I might have missed during the reassembly that would cause this problem? Or is this something that goes deeper, for instance, a problem with my motherboard?