How can display different panels using Request.queryString from one page to another?

Question

I want to redirect "Manage-Cat-Subcat.aspx" from "Mainpage.aspx" to display panel1 and panel2 according to the selection by ddlCat and ddlSubCat(Dropdownlist)...

Redirect to "Manage-Cat-Subcat.aspx" page to display Panel1:

protected void ddlcat_SelectedIndexChanged(object sender, EventArgs e)
{
    if (ddlcat.SelectedItem.Text == "Other...")
    {
        Response.Redirect("ManageCat-SubCat.aspx?Register=pnlCat");
    }
}

Redirect to "Manage-Cat-Subcat.aspx" page to display Panel2:

protected void ddlsubcat_SelectedIndexChanged(object sender, EventArgs e)

{
    if (ddlsubcat.SelectedItem.Text == "Other...")
    {
        Response.Redirect("ManageCat-SubCat.aspx?Register=pnlSubCat");

    }

}

This is what i did try in Manage-Cat_Subcat.aspx to display according to the value in 'Register'

protected void Page_Load(object sender, EventArgs e)
{
    if (Request.QueryString["Register"] = pnlCat)
    {
        Panel1.Visible = true;
    }
    else if (Request.QueryString["Register"] = pnlSubCat)
    {
        Panel2.Visible = true;
    }

Thanks!!

Answer 1

Main Page

protected void ddlcat_SelectedIndexChanged(object sender, EventArgs e)
{
    if (ddlcat.SelectedItem.Text == "Other...")
    {
        Response.Redirect("ManageCat-SubCat.aspx?Register=pnlCat");
    }
}

protected void ddlsubcat_SelectedIndexChanged(object sender, EventArgs e)

{
    if (ddlsubcat.SelectedItem.Text == "Other...")
    {
        Response.Redirect("ManageCat-SubCat.aspx?Register=pnlSubCat");

    }

}

Manage-Cat-Subcat.aspx

protected void Page_Load(object sender, EventArgs e)
{
panel1.visible=false;
panel2.visible=false;
if(Request.QueryString["Register"]=="pnlCat")
{
panel1.visible=true;
}
if(Request.QueryString["Register"]=="pnlSubCat")
{
panel2.visible=true;
}
}