Plugin InputTextMask information is cleared when the field is not complete

[danilo]

Hello,
I use the plugin mask: InputTextMask
When user does not completely fill out this field, the field's value is erased.
How can I change this property?

<ext:TextField ID="txtCNPJ" runat="server" Width="127" AllowBlank="False" BlankText="O campo CNPJ é de preenchimento Obrigatório!" MaxLength="18">
<Plugins>
	<ux:InputTextMask ID="MaskCNPJ" runat="server" Mask="99.999.999/9999-99" />
</Plugins>
</ext:TextField>

Thanks!