How to explain the difference between microarray results and qPCR data - (Aug/29/2011 )

Hi, I am working on microRNA. Now I try to use qPCR(Taqman) to confirm microarray data. But there are several miRs the expressions of which are opposite to the data of microarray.(one shows going up, the other shows going down ) I think that qPCR results should be reliable, because I repeated many times. So I don't know how to explain this. Except to run more microarray, is there any other way to find out the real tendency of the expression?
Thanks

Probably this discrepancy has to do with the inherent difference between these two methods in detecting miRNA. Certainly PCR is more sensitive than microarray hybridization especially for those miRNAs which are highly homologous to other members in the same family.