Hi Nutty,
If you are using BI 4.1 SP7 then you have to install Exactly Same version of Designer to the Client Machine.
So, You need to install Crystal Reports Designer 2013 SP7 .
P.S >>> 2013 is BI 4.1 and 2016 is BI 4.2.
You might have a question why cant I install Latest one i.e. 2016. So, According to the KBA : 1376876 - SAP BusinessObjects products and components should be updated to the same Patch version level
You have to use exactly same version of Client tools to connect to Server. Any other combination of higher/lower level of Server and Client will fall outside the support boundaries.
regards,
Mahak