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>