c# - Asp.net ListView commandArgument of a button is empty

Question

This is my .aspx page

<asp:ListView ID="ListViewGSMatches" runat="server" SelectMethod="ListViewGSMatches_GetData" DataKeyNames="id" UpdateMethod="ListViewGSMatches_UpdateData">
    <LayoutTemplate>
        .
        .
        .
    </LayoutTemplate>
    <ItemTemplate>
       .
       .
       .
    </ItemTemplate>
    <EditItemTemplate>    
        <asp:ListView ID="ListViewPlayerStatisticsHome" runat="server" DataSource='<%# GetPlayerStatistics(Eval("participant1Id"), Eval("id"))%>' DataKeyNames="id" OnItemCommand="ListViewPlayerStatisticsHome_OnItemCommand">
            <LayoutTemplate>
                <span>Off. Statistics</span>
                <asp:TextBox runat="server" ID="TxbOffensiveStatistics"></asp:TextBox>
                <span>Def. Statistics</span>
                <asp:TextBox runat="server" ID="TxbDefensiveStatistics"></asp:TextBox>
                <asp:Button runat="server" Text="Update" ID="UpdateButton" CommandName="UpdateStatistics" CommandArgument='<%# Eval("matchId") + "/2" %>' ClientIDMode="Static" />
            </LayoutTemplate>
            <ItemTemplate>
                   .
                   .
                   .
             </ItemTemplate>
        </asp:ListView>
    </EditItemTemplate>    
</asp:ListView>

And this is .cs file

protected void ListViewPlayerStatisticsHome_OnItemCommand(object sender, ListViewCommandEventArgs e)
{
    var ca = e.CommandArgument;
    var cn = e.CommandName;
}

My problem is that CommandArgument is empty string when using CommandArgument='<%# Eval("matchId") + "/2" %>'. When i set CommandArgument like this: CommandArgument="1", i can access CommandArgument in code behind. I also tried onCLick event, but again, CommandArgument was empty when using databinding expression.

Why is databinding not working for me in this case ? Is it because of nested ListView ?(I have found many examples using databinding expression to set commandArgument)

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