How to close this Modeless Form

Hi Guys,
I have no hair left after fighting with this issue for a couple of days.

I have a DCL dialogue box that calls an OpenDCL modeless dialogue box to display steel section dimensions.
Modeless, because I want it open while I draw the necessary information from the figured dimensions that will be shown in the modeless dialogue box.
When I',m finished drawing I want to close the Modeless form... but I can't, it won't let me.

I know, I could rewrite the complete existing AutoLISP code using OpenDCL dialogue forms, but that would take forever.

I appreciate any help and slap across the face for an obvious lack of knowledge and errors.

Regards.

Maybe this helps:

(defun C:STEEL_DIMS ( / dcl_id ret)

   (setq dcl_id (load_dialog "STEEL_DIMS.dcl"))

   (if (not (new_dialog "STEEL_DIMS" dcl_id)) (exit))

   (action_tile "DISPLAY_SLIDE" "(done_dialog 2)")

   ; (action_tile "accept" "(done_dialog 1)")

   (action_tile "cancel" "(done_dialog 0)")

   (setq ret (start_dialog))

   (unload_dialog dcl_id)

   (if (= 2 ret)

      (sps)

   )

   (princ)

)

Thanks, Roy,
Obvious now to close the ACAD dialogue before opening the OPENDCL form now that I see it.

Sometimes, wood and trees just look the same.
Thanks again.