I have a reseller account with HG and signed up a client who wanted to get their own hosting/reseller account package. Acting on behalf of my client and using my IP, I signed them up through one of my HG affiliate links.
It didn't register/show in my affiliate stats so I contacted support. At first, they said that they pay thousands of people every day to which I replied, that's fine for the thousands of people but how about paying me.
Basically, they kept re-stating that technically, if it didn't register, then they weren't going to and didn't have to pay.
After a bit of polite debating, explaining the details and 9 support tickets later, I finally got an understanding supervisor who said to email them in 30 days to verify my client was still registered, which I did and they paid.
Not suggesting that this approach will work all of the time if your link doesn't register, but it's always worth a shot.
Cheers