Trying to move Checkbox Items in Gridview to Listb

I am working on an assignment that is asking me to use code to create a gridview with a checkbox. After doing so, I am to take the checkbox items selected (through a button click) over to the listbox to display the values as text.

The sample page is here: http://aspnet.cob.ohio.edu/mis3200/asppub/MIS3200/Unit8/bobcat8POS.aspx

My code so far is this:

 protected void btnSelect_Click(object sender, EventArgs e)
{

    lblAlready.Text = string.Empty; // empty the label that says you already have an item

    foreach (GridViewRow row in gvSnacktastic.Rows) // check all the items in the grid view
    {
        CheckBox checkItOut = row.Cells[0].Controls[0] as CheckBox; // get the checkbox
        if (checkItOut != null && checkItOut.Checked) // if the checkbox exists and is checked
        {
              bool storeVariable = true; // store a variable that tells us if we need to add it to the list

            foreach(ListItem listItem in lbSelected.Items)  // Loop through list box items to see if we already have it. i haven't used listbox in a long time, this might be slightly wrong 
              {
                    // I'm not sure if it's .Text - compare the text of the listbox item to the checkbox item description
                    if(listItem.Text== checkItOut.Text)
                    {
                         lblAlready.Text = "The Item " + listItem.Text + " has already been added."; // make our already added label
                         storeVariable = false; //  we don't need to add this item
                    } 
              }
              if(storeVariable) // if we do need to add this item
              {
                  lbSelected.Items.Add(checkItOut.Text); // create a new list box item with the check box item's description 
               }
        }
    }
}

It doesn't display any errors, but when I run the page the select button does not do what I want it to. Would anyone be willing to look at the sample page and let me know what I am missing in my code?

<asp:GridView ID="gvSnacktastic" runat="server" AutoGenerateColumns="False" 
                                DataKeyNames="SID" DataSourceID="sdsSnacktastic" Visible="False">
                                <Columns>
                                    <asp:TemplateField>
                                        <ItemTemplate>
                                            <asp:CheckBox ID="cbSnacktastic" runat="server" />
                                        </ItemTemplate>
                                    </asp:TemplateField>
                                    <asp:CommandField ButtonType="Button" ShowSelectButton="True" Visible="False" />
                                    <asp:BoundField DataField="SID" HeaderText="SID" InsertVisible="False" 
                                        ReadOnly="True" SortExpression="SID" Visible="False" />
                                    <asp:BoundField DataField="Description" HeaderText="Description" 
                                        SortExpression="Description" />
                                    <asp:BoundField DataField="Price" DataFormatString="{0:c2}" HeaderText="Price" 
                                        SortExpression="Price" />
                                </Columns>
                            </asp:GridView>

Here you go.

Issue is that in your if condition you check with the text of the checkbox instead of the text of the 1st column.

Update:

protected void buttonSubmit_OnClick(object sender, EventArgs e)
{
    lblAlready.Text = string.Empty; // empty the label that says you already have an item

    foreach (GridViewRow row in gvSnacktastic.Rows) // check all the items in the grid view
    {
        var checkItOut = row.FindControl("checkItOut") as CheckBox; // get the checkbox

        // if the checkbox exists and is checked
        if (checkItOut == null || !checkItOut.Checked)
        {
            continue;
        }

        var storeVariable = true; // store a variable that tells us if we need to add it to the list

        // Loop through list box items to see if we already have it. i haven't used listbox in a long time, this might be slightly wrong 
        foreach (ListItem listItem in this.lbSelected.Items)  
        {
            // I'm not sure if it's .Text - compare the text of the listbox item to the checkbox item description
            if (listItem.Text != row.Cells[3].Text)
            {
                continue;
            }

            // make our already added label
            this.lblAlready.Text = "The Item " + listItem.Text + " has already been added."; 

            // we don't need to add this item
            storeVariable = false;
        }

        // if we do need to add this item
        if (storeVariable) 
        {
            this.lbSelected.Items.Add(row.Cells[3].Text); // create a new list box item with the check box item's description 
        }

        checkItOut.Checked = false;
    }
}