It depends on the practices of your lender - while most automatically report to all 3, some smaller lenders/credit unions/etc. may not routinely report to them all. There is no requirement that a creditor (lender) report to any or all of them - only that if they do report, they do it correctly.
Also, sometimes one or more of the big 3 CRA's will be behind the others for a cycle or two, and will eventually catch up, Strangely enough, for me TU is usually the last one to add/change something, not the first.
