You don't mention if the target client does get the policy, at all, for the Task Sequence. If you use something like Roger Zanders' Client Center to remotely look at the device targeted, does the TS even show up as listed?
Do any steps run?
If the TS does show up, what if you add just a single task to do something boring, like copy a file from %windir%\system32 to c:\windows\temp\JustTesting.txt ? just to see if the TS is doing anything at all, and it's just the posh individual task that isn't doing anything?