Validating receipt with App Store in sandbox mode

I'm having some trouble testing my in app subscriptions. To know where to start I would like to know if a recepit can be validated (in sandbox mode of course) even if it's not approved by apple. I get an error code which I can'r reproduce right now because of my next problem below:

Secondly, I get Error Domain=SKErrorDomain Code=2 "Could not connect to iTunes Store" a lot. It means "user cancelled the request, etc." according to Apple, but I didn't cancel anything!

Every once in a while it works though, even though I'm not changing anything. I read somewhere that this has to do with me purchasing the same subscription twice, is that true? I really need to test a lot and it takes sooo much time waiting for this error to go away, which makes testing a real cumbersome task.

I tried to go in to subscription settings when the App Store tells me that I already has purchased the product, but I can开发者_如何学JAVA't seem to be able to log in there with my test user. I just get an "Could not connect to App Store".

Thanks!

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Right now, it may be because of the iOS 5 upgrading/activation stampede.