GPF in Oracle Forms 4.5.5.3.5

I'm trying to use the Windows Common Dialog (File Open) VBX in Oracle Forms 4.5.5.3.5. On the form, I have a button ('btn_open'), a text box ('txt_Filename') to store the returned filename, and the VBX Custom Item ('FILE_OPEN_VBX'). The code behind the button is below. When I click on the button, I get a GPF. When I click on the IGNORE button, the GPF goes away and the dialog box works great, no matter how many more times I open it in one session. I would greatly appreciate any help that can be offered.

Kevin McCallum
mccallkw_at_acq.osd.mil

The VBX Control Value Property is set to FileName

DECLARE
        PL_FILE VARCHAR2(240); BEGIN
          VBX.Set_Property('FILE_OPEN_VBX', 'Filter', 'All Files (*.*) |*.*|ExcelFiles(*.xls)|*.xls');

  	VBX.Set_Property('FILE_OPEN_VBX', 'FilterIndex', '1');
  	VBX.SET_PROPERTY('FILE_OPEN_VBX','Action','1'); 
  	pl_file := VBX.GET_PROPERTY('FILE_OPEN_VBX','Filename');
  	:txt_Filename := pl_file;
  	VBX.SET_PROPERTY('FILE_OPEN_VBX','Action','0'); 
   
  	go_item('btn_open');