[Solved] SQL Server Error: The data types nvarchar and nvarchar are incompatible in the subtract operator

Error: The data types nvarchar and nvarchar are incompatible in the subtract operator.

SELECT  (Pa.T_Amt-cs.Cs_Amt) as Received
FROM     tbl_Payable PA
inner join tbl_InvM I on I.I_ID=PA.I_ID
inner join tbl_Customer c on c.C_ID=I.C_ID
inner  join tbl_Vehicle V on v.V_ID=I.V_ID
inner join Tbl_CasRec cs on cs.I_ID=PA.I_ID