Getting following error while refreshing power pivot data in excel sheet,
we installed power pivot perfectly but somewhere some permission is missing but could not able to find it,

when i check event viewer, found following error though i m able to connect sql server instance from SharePoint box and able to ping,
can some one help me to fix this?
"OLE DB or ODBC error: A network-related or instance-specific error has occurred while establishing a connection to SQL Server. Server is not found or not accessible. Check if instance name is correct and if SQL Server is configured to allow
remote connections. For more information see SQL Server Books Online.; 08001; Client unable to establish connection; 08001; Encryption not supported on the client.; 08001."

Thanks,
Deepak Patel