Access ADP and Stored Procedure Did not Return Any Records

[Lin100]

Access ADP and Stored Procedure Did not Return Any Records
Access 2002 and SQL 2000 Server

I have a form named "Selector", and it have four combo boxes and a subform named Q_FilteringQuery_subform. When any of the combo box is selected, the code will
call a VBA procedure which will then activate the stored procedure named Get_Records_For_Selector_Form.
When I first select an item from the combo box Dept while all three other combo boxes are blank,
I got an error message:
Error Message "P1 is not a parameter for procedure Get_Records_For_Selector_Form"

Because of the error, no new records is displayed on the subform "Q_FilteringQuery_subform".

////////////////////////////////////////////////////////////////////////////////////////////////////////////

Private Sub Activate_Stored_Procedure_Tbtain_Records_For_Selector_Form()
Dim SQL_Form As String
Dim strStep As String

SQL_Form = "Exec [Get_Records_For_Selector_Form] "
strStep = ""

If Not IsNull(Forms!Selector!From_Date) And Not IsNull(Forms!Selector!To_Date) Then
SQL_Form = SQL_Form & strStep & " @From_Date = " & "'" & Me.From_Date & "'"
strStep = ","
SQL_Form = SQL_Form & strStep & " @To_Date = " & "'" & Me.To_Date & "'"
strStep = ","
End If

If Not IsNull(Me.Dept) Then 'Department
SQL_Form = SQL_Form & strStep & " @Department = " & "'" & Me.Dept & "'"
strStep = ","
End If

If Not IsNull(Me.so) Then 'SO_Number
SQL_Form = SQL_Form & strStep & " @SO_Number = " & "'" & Me.so & "'"
strStep = ","
End If

If Not IsNull(Me.Item) Then 'Item_Number
SQL_Form = SQL_Form & strStep & " @Item_Number = " & "'" & Me.Item & "'"
strStep = ","
End If

If Not IsNull(Me.Sectionno) Then 'Section_Number
SQL_Form = SQL_Form & strStep & " @Section_Number = " & "'" & Me.Sectionno & "'"
strStep = ","
End If

Me.Q_FilteringQuery_subform.Form.RecordSource = SQL_Form
End Sub

////////////////////////////////////////////////////////////////////////////////////////////////////////////

The stored procedure named Get_Records_For_Selector_Form
asked for 6 optional parameters.

CREATE PROCEDURE Get_Records_For_Selector_Form
@From_Date smalldatetime = Null, @To_Date smalldatetime = Null,
@Department int = Null, @SO_Number int = Null,
@Item_Number varchar(10) = Null,
@Section_Number nvarchar(3) = Null

AS SELECT DISTINCT [1_Job - Parent].SONumber, [1_Job - Parent].Department_Name, [1_Job - Parent].ItemNumber, [1_Job - Parent].SectNumber, [1_Job - Parent].RecordInitiateDate, [1_Job - Parent].MechUser, [1_Job - Parent].ElecUser, [1_Job - Parent].GreenTagUser, [1_Job - Parent].GreenTagDate, Ref_DepartmentID.ID
FROM Ref_DepartmentID RIGHT JOIN [1_Job - Parent]
ON Ref_DepartmentID.ID = [1_Job - Parent].DepartmentID
WHERE @From_Date >= isnull( @From_Date, dbo.[1_Job - Parent].RecordInitiateDate)
AND @To_Date <= isnull( @To_Date, dbo.[1_Job - Parent].RecordInitiateDate)
AND dbo.Ref_DepartmentID.ID = isnull(@Department, dbo.Ref_DepartmentID.ID)
AND SONumber = isnull(@SO_Number, dbo.[1_Job - Parent].SONumber)
AND ItemNumber = isnull(@Item_Number, dbo.[1_Job - Parent].ItemNumber)
AND SectNumber = isnull(@Section_Number, dbo.[1_Job - Parent].SectNumber)
ORDER BY [1_Job - Parent].RecordInitiateDate DESC
GO