I have 3 textboxes whose values are required to add up to 100. I am able to easily implement a javascript solution on the client.
However, I tried to use a simple routine in the code behind that went like this:
   Dim total As Integer
        total = CInt(TextBox1.Text) + CInt(TextBox2.Text) + _
                CInt TextBox3.Text)
        If total = 100 Then
            lblMsg.Visible = False
        Else
            lblMsg.Visible = True
        End If

Where lblMsg is error text. This proved unreliable, sometimes revealing the error message when total was indeed 100, sometimes leaving it invisible when it was not equal to 100.

I've given up on validation controls, as it seems they are only geared to validating one control at a time. Any ideas?

You can still use validation controls even though they seem to only validate one control. Set up a custom validator and create the handler for it. Then do your validation test based on the three controls. Set the validator validity based on the result.

Peter
------------------------------------------------------
Work smarter, not harder.

I took your advice and created a client function in Javascript to handle the validation. The validator needed a control to validate, so I created another textbox to store the sum value. I think I may be missing your point; are your suggesting a code behind function (server-side) instead?

Here's what I added: The Custom Validator (cleverly named)

<asp:CustomValidator id="CustomValidator1" style="Z-INDEX: 106; LEFT: 241px; POSITION: absolute; TOP: 225px" runat="server" ErrorMessage="Must add up to 100" ClientValidationFunction="PercentSum" ControlToValidate="TextBox4"></asp:CustomValidator>

And here is the client function:

<script language="javascript">
    function PercentSum(source, arguments){
        var theform = document.Form1;
        var a = parseInt(theform.TextBox1.value);
        var b = parseInt(theform.TextBox2.value);
        var c = parseInt(theform.TextBox3.value);
        document.Form1.TextBox4.value = a + b + c;
        var total = document.Form1.TextBox4.value;

        if(total == 100){
            arguments.IsValid = true;
        }else{
            arguments.IsValid = false;
        }
    }
    </script>

Peter-

Upon further review...
Ok, I get it now. The Custom validator is set to validate one of the textboxes, but the handler for the validator works with all 3 values and their total.

I implemented and tested this just now, and it works just as you described. Thanks a bunch, Peter (my best Lumbergh voice).

Hey Peter man turn on channel 9, check out this chick!

Sorry, couldn't help myself. You assistance is much appreciated.

-Colonel

:D LOL