I can't seem to get any sort of validator to fire when validating my DropDownList. I just want to make sure that it isn't left at "--Select--" when the user presses the Add button on the page. I've tried a range validator and required field validator and neither seem to fire at all. My DropDownList contains ID which is an int that is hidden and Name which is a string that is displayed. The ID is -1 for "--Select--".I use these all the time and can't understand why the page in this new solution is any different from other solutions I have done in the past. What have I missed?<asp:DropDownList ID="drpProducts" runat="server" CausesValidation="True" ValidationGroup="AddExistingProduct"></asp:DropDownList>
<asp:Button ID="btnAddExistingProduct" runat="server" Text="Add" onclick="btnAddExistingProduct_Click" ValidationGroup="AddExistingProduct" CausesValidation="true" />
<asp:RequiredFieldValidator ID="rfvAddExistingProduct" runat="server" Enabled="true" ValidationGroup="AddExistingProduct" ControlToValidate="drpProducts" InitialValue="-1" ErrorMessage="*"></asp:RequiredFieldValidator>
<asp:RangeValidator ID="
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