Not sure what is going on.... the previous version of DFP used the function:
the newer version uses:
wa_dfp_uploadfiles() (notice the 's')
I can see the code on your page references the new version, but the include file is still from the old version. I'm not sure exactly what is going on, but somehow your include file is out of synch with the code on the page.
What version of DFP do you have installed?