   [.net] RangeValidator not validating...
Protected Sub cmdB8_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles cmdB8.Click   RangeValidator6.MinimumValue = txtB8Min.Text   RangeValidator6.MaximumValue = txtB8Max.Text   RangeValidator6.Type = ValidationDataType.Double   Dim clearance As Double = Double.Parse(txtB6.Text) - Double.Parse(txtB7.Text)   txtB8.Text = clearance.ToString()   RangeValidator6.Validate()   If (RangeValidator6.IsValid = False) Then  txtB8.BackColor = Drawing.Color.Red   Else  txtB8.BackColor = Drawing.Color.White   End If    End SubIsValid keeps coming up as True, even though it should be False. What am I missing?If it helps the textboxes and buttons are in an updatepanel that's in a tabpanel. And validators are just in a tabpanel.   
  Is your UpdatePanel's UpdateMode set to Always? If not, it may be that the validator isn't seeing a value in txtB8. That would result in a false positive since validation always succeeds on an empty control (unless you use a RequiredFieldValidator).