What is " Businessobject XI 13.1"
There is BOE XI 3.1 which is version 12.x and then there is Cr for VS 2010 which is Version 13.0
And then there is BI 4.0 - Crystal Enterprise Framework Library version 14.0
Bottom line is it looks like you are mixing runtime.
As Bhushan said, if you are connecting to BOE 3.1 then VS 2008 and CR 2008 Install to get the runtime for connecting to BOE 3.1 is all that is required.
If you are using VS 2010 and BI 4.0 then use the Crystal Enterprise Framework Library 14.0 is BI 4.0 Enterprise and your project must be set to Framework 2.0 -> 3.5. BI 4.0 does not support 4,0 FW yet.
BI 4.0 is also Managed Reports only, meaning you cannot browse to a report folder to open the report, must Query the CMS to get the Report Object ID/CUID.
Crystal Reports Developer for Visual Studio 2010/2012 ( Version 13 ) does not include the 2 assemblies to connect to ANY Enterprise CMS Service.
And you cannot mix Runtime and BOE/BI server SDK's, they must be the same version, example BI 4.0 version 14.x runtime cannot talk to BOE 3.1 and CR 3.1 runtime cannot talk to BI 4.0 CMS.
Hope that's clear
Don