A big problem with avast scan

[phyniks]

Dear Mr Steckle,
I have a big problem with avast 4.8 and I hope it will be solved in the new version
I scanned my system (the deep deep one) with avast 4.8 and it didn't find any threat,then i scanned with MALWAREBYTES ANTIMALWARE,during the second scan,avast's ball wall spining,showing that the scan is monitored by avast too,and surprisingly avast found 3 trojans in the scan accomplished by Maawarebytes!!!
I checked the trojans with other AVs and they showed they were real trojans
I wanna know the cause...
Is it because the scan by avast is not as deeply as it should be??
and therefore some threats would be missing during the scan???
Thanks

[FreewheelinFrank]

The name and location of the files would help.

Did you have avast! set to look in archives?

[DavidR]

Check the avast! Log Viewer (right click the avast 'a' icon), Warning section, this contains information on all avast detections. C:\Program Files\Alwil Software\Avast4\ashLogV.exe
 
- Or check the source file using notepad C:\Program Files\Alwil Software\Avast4\DATA\log\Warning.log and copy and paste the entry.