Hello, Im using a GridPannel linked to a Store, the data appears correctly, but when a i click on button Remove, the page calls the postback and the data of the Store and Gird desappears. How can i fix it?

Store:
<ext:Store ID="storeViewState" runat="server">
        <Reader>
            <ext:JsonReader>
                <Fields>
                    <ext:RecordField Name="idTipoCurso" Type="String">
                    </ext:RecordField>
                </Fields>
            </ext:JsonReader>
        </Reader>
    </ext:Store>
I insert into Store's DataSource the Data, but when i click on this button

<ext:Button ID="btnExcluir" Text="&amp;nbsp;Excluir" runat="server" Icon="Delete">
        <Listeners>
                <Click Handler="excluir" />
        </Listeners>
</ext:Button>

He lost the references, what i need its record the Id into the postback that i need do delete from my DB.
I tried usa a ViewState, but i didnt work.

Please if someone could help me.