Changing source in Webi : unable to select a field for mapping

Dear gurus,

We are experiencing a strange behaviour of the changing source feature in Webi.

We are trying to change Source A to Source B, both bex queries, in a web document.

Source B as the same data but the name of the columns are different to enable dynamic names from BW. When we do the source change, Webi is not able to map all the columns. Some of the fields have the status "Remove"

So in the mapping table proposed by Webi, we try to change the value to map it to something we know is OK.

Here is the problem, we don't have the ability to push on the "OK" button after we chose the field...

Have you ever seen that behaviour ?

PY