Luc,
Zet in "Private Sub CommandButton4_Click()" net onder "Sheets("verrichtingen").Range("o100").End(xlUp).Offset(1) = TextBox41.Value" deze extra lijntjes
With Sheets("verrichtingen").[H2].Validation
.Delete
.Add Type:=xlValidateList, Formula1:="=$O$2:$O$" & Sheets("verrichtingen").Cells(1, 15).End(xlDown).Row
End With
Beter zo?