setup OPC server simulink

I try to communicate my simulink model to a PLC (just a few parameters).

Therefore, I installed a free OPC server (graybox).

When I open the OPC toolbox in simulink and try to add the graybox server in the opc config block, I receive an error (error using opcmex).

It seems the server is not correctly installed or something... How can I setp an OPC server to communicate with simulink?

[Kaustubha Govind]

I don't have any experience with OPC, but you should probably specify the exact error message that you receive.