Regarding portal application

Dear frds

I had developed an application which works fine in local NWDS

but when i deployed to portal i magetting Exception..

In my application i just get URL and just link out using Exit plug... so i am able to get another browser window with specified URL

If i run same application in portal i am getting

com.sap.tc.webdynpro.services.exceptions.WDRuntimeException: Exit-Plug must no be triggered with an URL when running in portal. Use portal navigation instead to navigate to another application!

how to get another broswer in portal do i need to do something?