Revit doesnt distinguish between line and beyond lines

[danezeq]

i made a section. one duct is behind another duct which is bigger and supposed to hide the smaller one, but the thing is i see both of them.
the desirable situation is to see the smaller (the one that behind) duct appearing on "beyond lines" (dashed lines). it's not happening. why?

I AM NOT ON WIREFRAME MODE.

[fabiosato]

Hello,

In the Mechanical settings, hidden lines is marked?

[danezeq · Accepted solution]

Found the sulution:

went to the duct system type properties > graphic overrides > pattern > clear the pattern.