Hi Mahesh,
Also could you check on the protocols like WebAS, ITS etc in sys obj properties.. usually it should be http.
Since the working and problematic iviews are pointing to same SAP system,
To check where is the issue, try to point the problematic tiview to the system object of the iview which is working ( in your case point tiview of PA20 to system object of phap_prepare_pa)
If its not giving a pop up now may be you can compare the system obj properties of both.
Regards
Uday