This is a very naive question, but I don't know much about this. I asked a [similar question before](https://money.stackexchange.com/questions/11078/transunion-is-unable-to-locate-credit-report-should-i-be-concerned), but the emphasis was different. I managed to get a credit report through Experian and Equifax (and the reports were pretty nice), but Transunion for some reason can't locate my report. Assuming I have only reports from 2 of these companies, and that for some reason nobody ever bothered to report me to Transunion; does this affect my credit score?

In other words, if I were to want something that needs a good credit score (say a mortgage), will this affect their decision? In particular, is the way they compute the credit score by averaging the credit scores from the three companies (and then it will be considered that I have a 0 or the like from Transunion)?

Thanks,
Nicole.