FSMETEO and QNH question.

Good Afternoon,I have noticed something strange while flying using FSMETEO.FSMETEO gives arrival qnh for example 1015. Passing the TL. If I press B for auto baro setting the QNH that is displyed is tottaly different like 1020. The strange is that the QNH inserted with B give the correct airport altitude at touch down while manually inserted qnh gives wrong airport alyitude. That is observed only using PMDG.I havr the latest FSUIPC in my Machine.Any ideas?Thx in advChris