Exception from AM_VIEW_PROP

Following LISP call throws exception for certain files.

(AM_VIEW_PROP :the_view viewPath :show_thread_lines :off :update_view)

viewPath is the actual path of the view i.e. sheetName/ViewName.

Intention is to turn off the display of thread lines for the view and we call it for all the views in the sheet.

What could be the reason?

PS> Ignore the smiley in the code above and read it as collonoff 🙂