How to embed variable value in sqldatasource session parameter in c#

[hery]

I want to question how to embed variable value in sqldatasource session parameter in c#. This is mycode:

default.aspx:

<asp:SqlDataSource ID="SqlDataSource1" runat="server" 
    ConnectionString="<%$ ConnectionStrings:Ora2011 %>" 
    ProviderName="<%$ ConnectionStrings:Ora2011.ProviderName %>" 
    SelectCommand="SELECT ID, CATEGORY_NAME FROM (:INVENT_CATEGORY)"> 
    <SelectParameters>
        <asp:SessionParameter Name="INVENT_CATEGORY" SessionField="INVENT_CATEGORY" Type="String" />
    </SelectParameters>     
</asp:SqlDataSource>

C#:

protected void Page_Load(object sender, EventArgs e)
{
    string table = "V_INVENTORY"
    Session["INVENT_CATEGORY"] = table;
}

When i run this program, i get error "invalid table name". Why i can't embed variable into sqldatasource from session parameter. Thanks for your help