SSRS Dynamic Connection String is not working.

Hello,

I have downloaded one Cube metadata report from the below link.

http://www.wrox.com/WileyCDA/WroxTitle/productCd-0470563117,descCd-DOWNLOAD.html

and customize the report by creating two parameter Server name  and Database so that we can change the server and database dynamically.
and change the embedded connection string as (="Data Source="+Parameters!ServerName.Value+";Initial Catalog="+Parameters!Database.Value)

every thing work as expected on my local report server, but if my colleague try to access the report throw my system they are getting error message.

⦁       An error has occurred during report processing. (rsProcessingAborted) 
⦁       Cannot create a connection to data source 'dsSSAS'. (rsErrorOpeningConnection) 
⦁       For more information about this error navigate to the report server on the local server machine, or enable remote errors

But without the dynamic connection string its working fine on my colleague system also.

may i know what i need to change so it can work with the dynamic connection string.

Thanks,
javed Khan.