BeforeUpdate event validation control - excel

Question

Dears,
I want to make a simple userform to record some serial numbers into excel, it contains a textbox_serialNo., a command button “enter” and another command button “cancel”.
I made a validation control in that serialNo textbox so that only number can be entered. However, when I run the program and input some numbers into the textbox, both command buttons (the "enter" button named as label_enter,the "cancel" button named as label_cancel) have no reactions (e.g. the "cancel" button doesn't unload the form when press) , how should I correct the program? Below are the relevant codes, Thanks.
Private Sub TextBox_SerialNo_BeforeUpdate(ByVal Cancel As MSForms.ReturnBoolean)
If Not IsNumeric(TextBox_SerialNo.Value) Then
TextBox_SerialNo.BackColor = rgbYellow
End If
Cancel = True
End Sub
Private Sub TextBox_SerialNo_AfterUpdate()
If TextBox_SerialNo.Value <> "" Then
TextBox_SerialNo.BackColor = rgbWhite
End If
End Sub
Private sub label_enter_click()
sheet1.Select
Cells(Rows.Count, 1).End(xlUp).Offset(1, 0).Select
ActiveCell.Value = ActiveCell.Offset(-1, 0).Value + 1
ActiveCell.Offset(0, 1) = TextBox_SerialNo.Value
TextBox_SerialNo.Value = ""
End Sub
Private Sub Label_Cancel_Click()
Unload Me
End Sub

Answer 1

Sorry to be posting as an answer, not enough rep.
Shouldn't Cancel=True be inside the if statement? You are locking it up regardless of entry being numeric or not as is.
Edit:
Actually upon further testing still not working proper. However, change event works better and you can get instant feedback for any non numerics.
Updated code would look like this, control names differ. I am used to working with .Text, same thing as .Value. Also, since I am not sure what you would do with an empty string, assumed it to be yellow background as well.
One concern would be, can you allow comma or period in there? Depending on locale settings, a decimal would also be considered a numeric.
Private Sub cmdCancel_Click()
Unload Me
End Sub
Private Sub cmdEnter_Click()
If TextBox1.BackColor = rgbYellow Then Exit Sub
test4.Range("A1").Value = TextBox1.Text
End Sub
Private Sub TextBox1_Change()
If Not IsNumeric(TextBox1.Text) Or TextBox1.Text = "" Then
TextBox1.BackColor = rgbYellow
Else
If TextBox1.Text <> "" Then
TextBox1.BackColor = rgbWhite
End If
End If
End Sub
Edit 2: I use this piece of code to check for only numbers (assuming number Ascii codes are standard). Maybe it can help.
Public Function isnumber(ByVal strValue As Variant) As Boolean
On Error Resume Next
Dim i As Long
isnumber = True
If Not strValue = "" Then
For i = 1 To Len(CStr(strValue))
If Asc(Mid(strValue, i, 1)) > 57 Or Asc(Mid(strValue, i, 1)) < 48 Then
isnumber = False
Exit For
End If
Next i
Else
isnumber = False
End If
On Error GoTo 0
Err.Clear
End Function
Edit 3: I have revised the TextBox1_Change event code so all invalid characters are stripped right away. However, in this state if you copy paste a serial no with a non-allowed char, it will strip them leaving only the numbers. Not sure if it is acceptable.
Private Sub TextBox1_Change()
If Not isnumber(TextBox1.Text) Or TextBox1.Text = "" Then
TextBox1.BackColor = rgbYellow
Dim i As Long
Dim strValue As String
strValue = ""
If Not TextBox1.Text = "" Then
For i = 1 To Len(CStr(TextBox1.Text))
If Not (Asc(Mid(TextBox1.Text, i, 1)) > 57 Or Asc(Mid(TextBox1.Text, i, 1)) < 48) Then
strValue = strValue & Mid(TextBox1.Text, i, 1)
End If
Next i
End If
TextBox1.Text = strValue
Else
If TextBox1.Text <> "" Then
TextBox1.BackColor = rgbWhite
End If
End If
End Sub