I have a 72 Cleric on Xegony, and the last several times I have logged onto that toon, I am unable to summon the Resupply Agent. Attempts to do so fail immediately, while my conjuration skill goes up a notch. Is anyone else experiencing this?
Are you using the default UI? If not using default you might try loading that and see if it fixes the problem. Worth checking that your pc time is accurate that can cause a few issues.
Please check if your buff list is full (the "Effects" window shown/hidden when you see press ALT-B). If so, remove a buff and try to re-summon the Resupply Agent again. EDIT: I had non-refreshed old thread contents showing, and now I see some people suggested this already before I did!