Error 'cannot get parameters of procedure dbo.fDepartment when calling sqlserver function

PB code sqlca.f_fdepartment( "Science") if sqlca.sqlcode= -1 then messagebox("Error",sqlca.sqlerrtext) end if FUNCTION  decimal  fdepartment(string  as_code) RPCFUNC ALIAS FOR 'dbo.ufDepartment' sqlserver function AlLTER  FUNCTION [dbo].[ufDepartment'](@department varchar(20)) RETURNS varchar(20) AS BEGIN declare lsdepartment varchar(20) lsdepartment  = "Test" Return lsdepartment end Please can you help where is the problem how to fix it Kind Regards Pol