LVS error for MOS parameters

Hello all,

     I got error message in LVS in parameters mismatch tool(Virtuoso XL), the message is :  

Err: Sch MOS missing params: l,w ; Lay MOS W/L/NF 5e-06 1.8e-07 12

     I don't have any idea about what this error means.If anyone has any idea about it then it will be a great help. Thank you.