The full path must be less than 260 characters long

Hello, 

I am working on Microsoft reporting services(SSRS 2012). 

Issues: On click of the a indicator it opens a new report through javascript. But some some values it is giving me error and the error is 

"The path of the item '/Reports/MethodM/EventSat_Report, 2' is not valid. The full path must be less than 260 characters long; other restrictions apply. If the report server is in native mode, the path must start with slash. (rsInvalidItemPath)"

thanks,

amit