ReadPermission in combination with RecRef

Hi

If have a strange issue with ReadPermission, NAV 2013R2.

This works
RecRef.OPEN(TableID);
If RecRef.READPERMISSION THEN…

This does not work (RunTimeError on first line of code, "Access is denied to Company <TheCompanyName>")
RecRef.OPEN(TableID,False,TheCompanyName);
If RecRef.READPERMISSION THEN…

So my problem is, code does not reach the line to test with ReadPermission, because the OPEN command fails.

Thanks in advance.
Thomas