U menya vse rabotaet:

Private Sub Command1_Click()
    MSHFlexGrid1.Sort = 9  'flexSortCustom
End Sub

Private Sub Form_Load()
    With MSHFlexGrid1
        .Cols = 2
        .AddItem 1 & vbTab & Date
        .AddItem 2 & vbTab & Date - 1
        .AddItem 3 & vbTab & Date + 1
        .AddItem 4 & vbTab & Date - 5
    End With
End Sub

Private Sub MSHFlexGrid1_Compare(ByVal Row1 As Long, ByVal Row2 As Long, Cmp As Integer)
    CustomSort MSHFlexGrid1, 1, Row1, Row2, Cmp, True
End Sub

Private Sub CustomSort(ByRef pGrid As MSHFlexGrid, _
                       ByVal pCol As Long, _
                       ByVal pRow1 As Long, _
                       ByVal pRow2 As Long, _
                       ByRef pCmp As Integer, _
                       ByRef pSortAscending As Boolean)

    Dim varRow1 As Variant
    Dim varRow2 As Variant

    On Error GoTo MethodError

    With pGrid
   
        If IsNumeric(.TextMatrix(pRow1, pCol)) And IsNumeric(.TextMatrix(pRow2, pCol)) Then
       
            varRow1 = CDbl(.TextMatrix(pRow1, pCol))
            varRow2 = CDbl(.TextMatrix(pRow2, pCol))

        ElseIf IsDate(.TextMatrix(pRow1, pCol)) And IsDate(.TextMatrix(pRow2, pCol)) Then
       
            varRow1 = CDate(.TextMatrix(pRow1, pCol))
            varRow2 = CDate(.TextMatrix(pRow2, pCol))
           
        Else
       
            varRow1 = CStr(Trim$(.TextMatrix(pRow1, pCol)))
            varRow2 = CStr(Trim$(.TextMatrix(pRow2, pCol)))
                   
        End If
       
        If varRow1 < varRow2 Then
            pCmp = -1
        ElseIf varRow1 > varRow2 Then
            pCmp = 1
        Else
            pCmp = 0
        End If
       
        If Not pSortAscending Then
            pCmp = pCmp * -1
        End If
       
    End With

MethodError:
    If Err.Number <> 0 Then
        MsgBox "Error " & Err.Description & " in CustomSort"
    End If
  
End Sub

У меня тоже все замечательно работает!

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