External datasource in report studio

[Shamar]

Hi Gurus !!!

I need to use Excel as external datasource in report studio. I can able to import excel data , after that i need to bring the existing report to do the mapping between excel and report. But when I browse for existing report it keeps on loading for more than half an hour.
Here my question is :
Does external datasource supports with multidimensional report ? if not please provide alternate solution.
Any guess why the existing report is not loading properly ?

source : cognos 10.2
DB : sql Server
Datasource : Cube

Thanks