Run-time error 438 Object Doesn't support this property or method

[Gaetanm via AccessMonster.com]

I have a form called Clock_Stop_Table
The purpose of this form is to UPDATE a existing record in the
Clock_Table

It consist of 4 fields and 2 buttons

ComboBox with the query [Jobs not Completed] that’s made up of 3 linked
tables.

EmployeeId, FirstName, LastName, JobID, Notes, StartDate, StopDate
Number Number Txt Date/Time
Date/Time

Is Not NULL Is Null

2 text boxes
JobID Lable =EmployeeId.Column(4) {deleted Lable} =EmployeeId.Column(5)

StopDate This Field is populated by a button [Input Stop Time}

Date/Time

The Input Stop Time button states:

Private Sub Command4_Click()
Me.StopDate = Now
End Sub

Now is where I think I’m getting into trouble !

This button should UPDATE the table called Clock_Table the table has the
following:

JobID EmployeeId StopDate StartDate
Number Number Date/Time DateTime

Here is the Code for the button:

Private Sub Command21_Click()

Dim SQLstrg As String

SQLstrg = "UPDATE Clock_Table SET [StopDate] = #" & Me.StopDate & "# WHERE ((
[StopDate] Is Null) And ([EmployeeID] = " & Me.[EmployeeID].[Column(0)] & "))
;"

End Sub
After clicking the button I get

"Run-time error 438 Object Doesn't support this property or method"

Has anyone any Ideas?
Gaetanm