ENBLLWTDSP : i need lineweight on sheet not in model space

I am drawing with DS V1R1.4 and i need to display lineweight only on sheets and not on model.

When i toggle ENBLLWTDSP on any one of these spaces, the action is seen in the two spaces. I don't find explanation in the help for this system variable.

Wher eis my error and how to do correctly ?

Thanks in anticipation