Hi Hector,
try to remove these lines :
oPick.Lines.BatchNumbers.Add();
oPick.Lines.BinAllocations.Add();
They are not needed in your example, since the lines are already present ( .Add() adds a new empty line ). But apart from that you got a rather specific error message : For me it sounds like the previsouly successfully picked batch for item "DTC-C73-PVC3-000" is not available anymore when you execute your update.
regards,
Maik