SAP BO 4.1- Webi over Bex Problem

HI All ,

we are at Bo 4.1 sp1 Batch 1

I am running report in web intelligence over SAP Bex query

the report has user parameters defined in BO (query panel)- all optional

when the user enters some of the parameters as(year/material) and so on- the report retrieves data

when the user do not enter any parameter e.g- run on all data - then the webi runs about 158 seconds , and retrieves no data at all

when i run the bex on rsrt - it runs very fast with no user prompts

is there a time limitation for data retrieval or some other definition in system?

any ideas?

thanks