SA0231 : The used parameter or variable has different case than its declaration

 1create procedure SampleProcedure
 2@EmployeeIDParm int,
 3@EmployeeFirstnameParm nvarchar(50),
 4@EmployeeLastnameParm nvarchar(50),
 5@maxTotal int output
 6as 
 7begin
 8    declare @myCounter int;
 9    declare @lastName nvarchar(30),
10            @firstName nvarchar(20),
11            @StateProvince nchar(2);
12
13    execute @MyCounter=sp_executesql 'select 1,2,3',
14            @params='',
15            @EmployeeIDParm=1,
16            @EmployeelastnameParm=@EmployeelastnameParm,
17            @EMPLOYEEIDPARM,
18            @maxTotal=@maxTotal output;
19
20    select @maxtotal,
21           @EmployeeLastNameParm,
22           @stateProvince,
23           @firstName,
24           @lastname;
25
26    return 1
27end