The problem is in the calculation of the values for the combobox.
If I use the result of the @Dblookup as is, it refuse to save. If I @Trim the result of the @Dblookup there is no problem.
I don't know what's cause the problem. The Xpage ? Server ? Browser ?
I've copied the XPages application on the different 8.5.3 UPG 1 server and with same browser and client it works even without the trim of the dblookup result