Invalid procedure call or argument error

When pressing a command button the code below is executed, and it results in an error as seen in the picture. In addition, I seem to be the only user with this issue. My coworkers don't mention having this issue. I never had this issue until about a month ago.

Cmd button Code: Private Sub cmdCheck_Click()

On Error GoTo Err_Close_Jobs

Dim i As Integer

' check in our list

If MySel(Me!Cat) Then

' already in list - remove

CheckItems.Remove CStr(Me!Cat)

Else

' not in the list - add it

CheckItems.Add Me!Cat.Value, CStr(Me!Cat)

' Debug.Print CheckItems

End If

Me.ckSel.Requery

Exit_Close_Jobs:

Exit Sub

Err_Close_Jobs:

MsgBox Err.Number & "/" & Err.Description

Resume Exit_Close_Jobs

End Sub

Code:

Public CheckItems As New Collection

Private Sub cmdCheck_Click()

On Error GoTo Err_Close_Jobs

Dim i As Integer

' check in our list

If MySel(Me!Cat) Then

' already in list - remove

CheckItems.Remove CStr(Me!Cat)

Else

' not in the list - add it

CheckItems.Add Me!Cat.Value, CStr(Me!Cat)

' Debug.Print CheckItems

End If

Me.ckSel.Requery

Exit_Close_Jobs:

Exit Sub

Err_Close_Jobs:

MsgBox Err.Number & "/" & Err.Description

Resume Exit_Close_Jobs

End Sub