iview connection time out error

We have an Transactional iView (Tcode KE30).

When we are executing in R/3 it is taking only 3minitues to execute

But in Portal it is not opening we are getting error like

500 Connection timed out

Connection timed out (-5)

Error: -5

Version: 6040

Component: ICM

Date/Time: Fri May 5 15:31:08 2006

Module: icxxthr_mt.c

Line: 2559

Server: ERPPRDA2_RP1_03

Detail: Connection to partner timed out

But we did not changed the default iView Properties.

What could be the reason and how to rectify it.

Plz do this need for me.

Regards

Srikanth