Automation of PDF Forms with Adobe Reader

[AjayW]

I am facing some issues with the automation of Pdf forms. the issue is the Adobe reader hangs while setting values to objects( Mostly on List Object). QTP is able to identify the Objects and execute the scripts but Reader hangs at random object while setting the value.
I have below setUp.
QTP -11
APTT AcroQTP Addin - 10.1.2.45
Adobe Reader - 10.1.4

Code:

PDFDoc("xx").AcroXFAForm("xx").AcroXFAForm("xx").AcroXFAListBox("Obj1").Select
If PDFDoc("xx").AcroXFAFormx("xx").AcroXFAForm("xx").AcroXFAListBox("Obj1").Exist(3) Then
    PDFDoc("xx").AcroXFAForm("xx").AcroXFAForm("xx").AcroXFAListBox("Obj1").Setvalue "ajayW"
End If

Note: -I can't use any more older version of Adobe Reader

Please guide me to resolve this issue.