rsErrorOpeningConnection Error when trying to access with c#

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C#

SQL-Server

SSRS

HI i had a requirement where i need to render the report from .net and save it as a pdf , i have two rdl's one rdl has a datasource pointing to server A, and the other rdl pointing to server b, and i have my report server configured to with server A, so when i try to priview it both the rdl's are working fine , when i deployed to report server the server A rdl is working fine but the 2nd rdl which is connected to server B has some connection related error (rsErrorOpeningConnection), wha is the reason for this error is this because of the datasource pointing to server b instead of server a where reportserver is configured or is there any other reason , and is there any fix for it ,please help me out thanks