Was the survey an actual market research survey? Or was it just a lead generation/co-reg offer?
If it was an actual research survey there may be several reasons the offer did not credit. Anti-fraud measures are put in place to make sure that real people are taking the survey and that they are actually paying attention to the survey and not just clicking check boxes to get through it and get paid.
If your five friends all took the same survey from the same computer or ip that could throw a flag up too as most surveys only accept one respondent or account per household.
There is alot of fraud in the online survey industry. And there are actually exploits people can use to bypass surveys and receive credit from affiliates. Doing a search for "daily surveys exploit" will show you exactly what I'm talking about.
Most networks or affiliate sites that run daily survey offers have a system in place to prevent this type of fraud. For our panel we give the user or affiliate a 'pending' credit when a survey reaches our end page. We update those credits to 'approved' when they are confirmed by the client. This insures that our pages cannot be manipulated and that we payout on every survey that the client credits us with.
Some surveys do not return the user back to our pages at the end. In these cases a pending credit will not immediately show in an account, but will still be credited the follwing day when we update the clients confirmations.
Research surveys do not usually have simple pixels or postbacks. You usually give the client two or three end pages to send the user to if they do not qualify for a survey, the survey has met its quota or the survey has been completed. If the survey is brokered from a third party we may not be able to set end pages and therefore have to rely on the records from the client. In this case leads would not show in real-time, but would show when we received confirmation from the client.
There is a lot of money that can be made running surveys. Especially daily surveys that your users can qualify for day after day.
But before running actual survey campaigns one should understand the market research business. And if anything is not understood it would be best to contact your affiliate manager.