combobox clearing

[angietate1]

My comboboxes keep clearing. I'm a new user to comboboxes and VBA. The three drop downs are cascading and they clear to soon or they won't stay selected. Help! Is there a way to attach the document?

Private Sub Combobox21_change()
Dim wsData As Worksheet
Dim listOfValues As String 'To store list of values already added
Dim ValueToAdd As String 'To store new value to add
listOfValues = ""
Set wsData = ThisWorkbook.Sheets("DATA")


MyVal = Me.ComboBox21.Value


'loop thru col a
lr = ThisWorkbook.Sheets("data").Cells(Rows.Count, 1).End(xlUp).Row


'clear combobox 22
Me.ComboBox22.Clear


'loop thru
For x = 2 To lr
If MyVal = wsData.Cells(x, 1) Then
'add to combobox
ValueToAdd = wsData.Cells(x, 2) 'Get value from worksheet
If InStr(listOfValues, ValueToAdd) = 0 Then
'Check to see if the value has already been added
'If not, add to values added and add the item to the combobox.
listOfValues = listOfValues & ValueToAdd
Me.ComboBox22.AddItem ValueToAdd
End If
End If
Next x

End Sub


Private Sub ComboBox22_Change()
Dim wsData As Worksheet
Dim listOfValues As String 'To store list of values already added
Dim ValueToAdd As String 'To store new value to add
listOfValues = ""
Set wsData = ThisWorkbook.Sheets("DATA")


MyVal = Me.ComboBox22.Value


'loop thru col b
lr = ThisWorkbook.Sheets("data").Cells(Rows.Count, 1).End(xlUp).Row


'clear combobox 23
Me.ComboBox23.Clear


'loop thru
For x = 2 To lr
If MyVal = wsData.Cells(x, 2) Then
'add to combobox
ValueToAdd = wsData.Cells(x, 3) 'Get value from worksheet
If InStr(listOfValues, ValueToAdd) = 0 Then
'Check to see if the value has already been added
'If not, add to values added and add the item to the combobox.
listOfValues = listOfValues & ValueToAdd
Me.ComboBox23.AddItem ValueToAdd
End If
End If
Next x

End Sub