Lines formated as Dash not saved

I need to format some lines on my drawings as Dash (tiny).  However, if I change the line format via Modify Properties, it correctly appears on screen, but if I save the drawing and reopen it the line has reverted to continuous.  I have tried putting the lines needed to be Dash (tiny) in a separate layer but it still makes them continuous after close and reopen.  The layer option does not seem to save correctly either if you set the layer to Dash (tiny) and save it reverts to Continuous when you reopen the drawing.

What am I doing wrong!!!!