Um, there's been a huge amount of conversation net-wide since October about Clickbank acting extremely screwy - not tracking sales, showing statistically impossible sales fluctuations, and basically having huge technical issues. They've even started to admit frequent outages on one of their update pages that they hide away on their site - but they're admitting to a very small percentage of the problems they're actually having.
I've seen major problems in both my publisher and affiliate accounts since October so I've stopped promoting them except in a few places where I can't find comparable products at paydot.com or e=junkie to promote.
I dont' recommend working with them at this point.
Remember too that they use PayPal as their processor. So if something is screwy between them and Paypal (and we all know Paypal can be messed up) then Clickbank has problems.
Dan