I am trying to implement the StoreKit on iPhone 3.1.3 and keep getting the invalidProductIdentifier error.

The question I have is the productKey used in following two methods the same?

SKProductsRequest *request= [[SKProductsRequest alloc] initWithProductIdentifiers: [NSSet setWithObject: @"com.companyName.productName.upgrade"]];

SKPayment *payment = [SKPayment paymentWithProductIdentifier:@"com.companyName.productName.upgrade"];

The reason i as is because I have tried different productIdentifiers and SKProductsRequest always comes back with invalidProductIdentifier but SKPayment returns SKErrorUnknown for almost all the productIdentifier I tried but interestingly returns SKErrorPaymentInvalid for the @"com.companyName.productName.upgrade" (with the companyName and productName substituted).

Any help would be appreciated.