Thanks for your help.
I have added : drop tables Table1, Table2 but then I lose my tables and still don't get the merged table
Could it come from the fact that I renamed fields in when I first load the resident tables ? I mean I have :
field1 as key,
FROM .... (qvd);
F1 as key,
FROM ... (qvd);
But I don't think so because when I don't try to join them, the link is done by qlikview.
Any other ideas ?