Problem with calling URL from web dynpro .

When I enter the URL( with parameters ) manually in the browser it works i.e. it populates the data in the pop ups for the selection screen and goes to the final selection screen and populates that selection screen via the URL parameters.

http://........./sap/bc/gui/sap/its/webgui?sap-client=030&~transaction=*ZTrans1 TKA01-KOKRS=A1;PROJ-PSPID=P-A72;PRPS_R-POSID=P-A720-99-99-7049;DYNP_OKCODE=/0

However , When I cal this same URL via

Call Method lo_window_manager->create_external_window

It does not by pass the pops ups and does not pass the URL parameters to the Pop ups

Any idea why this happens ? Please advise