Why is this CustomValidator client function not firing? - asp.net

Question

I have a dropdown with the Id of "BACKGROUND" and if nothing is selected or the value is other, it should fire my client side validation function, but it is not. Am I missing something?
I have the following client side function:
function cv26(oSrc, args) {//BACKGROUND,BG_OTHER
alert("cv26");
var otherCtrl = document.getElementById("BG_OTHER");
args.IsValid = (args.Value != " ") || (otherCtrl.value.length > 0);
}
My Custom validator looks like this:
<asp:CustomValidator ID="cv26" runat="server" ErrorMessage="26. Background is required." ControlToValidate="BACKGROUND" ClientValidationFunction="cv26" Display="Dynamic" ValidateEmptyText="true">*</asp:CustomValidator>

Answer 1

The problem is the value in ClientValidationFunction. It should be ClientValidationFunction="cv26" as it cannot find val_cv26
Change this:
<asp:CustomValidator ID="cv26" runat="server"
ErrorMessage="26.
Background is required."
ControlToValidate="BACKGROUND"
ClientValidationFunction="val_cv26"
Display="Dynamic"
ValidateEmptyText="true">*</asp:CustomValidator>
To:
<asp:CustomValidator ID="cv26" runat="server"
ErrorMessage="26.
Background is required."
ControlToValidate="BACKGROUND"
ClientValidationFunction="cv26"
Display="Dynamic"
ValidateEmptyText="true">*</asp:CustomValidator>
Or rename your JavaScript function to val_cv26.

Answer 2

Problem #1: Function names DO NOT MATCH
ClientValidationFunction does not match the function name.
In your javascript you declare function cv26, but in your CustomValidator you have val_cv26 for ClientValidationFunction. So you either change your javascript function to val_cv26 or change the ClientValidationFunction to cv26
Problem #2: Validation Groups
In your original code you did not specify any validation groups. Notice that both the CustomValidator and Button2 have ValidationGroup="hi". They must belong to the same validation group. You need validation groups if you have multiple buttons for example and you only want one of the buttons to validate user input. If you only have ONE button then this is not a problem.
ASPX:
<asp:DropDownList ID="BACKGROUND" runat="server">
<asp:ListItem Text=" --- SELECT ---" Value=""></asp:ListItem>
<asp:ListItem Text="A"></asp:ListItem>
<asp:ListItem Text="B"></asp:ListItem>
<asp:ListItem Text="C"></asp:ListItem>
</asp:DropDownList>
<asp:CustomValidator ID="cv26" runat="server"
ErrorMessage="26. Background is required."
ControlToValidate="BACKGROUND"
ClientValidationFunction="cv26"
Display="Dynamic" ValidateEmptyText="true"
ValidationGroup="hi">*</asp:CustomValidator>
<asp:Button ID="Button1" runat="server"
Text="Submit" onclick="Button1_Click"
ValidationGroup="hi" />
JavaScript:
function cv26(oSrc, args) {
args.IsValid = (args.Value != "");
}
When is your validation expected to fire?
Please provide the declaration for BACKGROUND
Please provide the declaration for BG_Other
Are BACKGROUND and BG_OTHER on the same ASPX page?