When i make a wall joined with another one that are not the same
(height,fill) the contour line in the joint ,sometimes appears and sometimes not.
I try the feature "wall end lines" but it doesn't work to much.
Am i doing something wrong
I think it is intended. If you join walls' axis it will clean up the line between them, no matter if they have different height, width, level, fill etc. If you need line, just draw one or hit F7 to switch off " clean wall intersection".