RequiredFieldValidator validates incorrectly (endlessly)

I several pages of forms and the

RequiredFieldValidator

does not allow the form to be submitted because it validates incorrectly asking user to enter data even though the data is entered! Sample code is below.

<asp:Label ID="TotalBedroomsLabel" runat="server" Text="Total number of bedrooms" class="control-label asterisk" AssociatedControlID="TotalBedrooms" meta:resourcekey="TotalBedroomsLabelResource1"></asp:Label><div class="controls"><asp:TextBox ID="TotalBedrooms" runat="server" class="input-xlarge" placeholder="" meta:resourcekey="TotalBedroomsResource1"></asp:TextBox><p class="help-block"><asp:RequiredFieldValidator ControlToValidate="TotalBedrooms" EnableClientScript="False" ID="RequiredFieldValidator5" runat="server" ErrorMessage="Please enter total number of bedrooms" meta:resourcekey="RequiredFieldValidator5Resource1"></asp:RequiredFieldValidator></p></div>

Never seen this behaviour before. Any ideas? Thanks.