GridView with Checkbox in ASP.NET

I am use Visual Studio 2008 to coding ASP.NET in C#

I am trying to get value checked or unchecked form checkbox in Gridview. This is my code to do.

void imbTransferBySelect_Click(object sender, ImageClickEventArgs e)
{
    for (int i = 0; i < GridView1.Rows.Count; i++)
    {
        CheckBox cb = (CheckBox)GridView1.Rows[i].FindControl("Transfer_Selector");
        if (cb.Checked)
        {
            //do something
        }
    }
}

When the checkbox is unchecked the code runs fine.

But when checkbox is checked value of GridView1.Rows.Count = 0 it's make for loop is fail

I try use another code in http://ift.tt/1FBt6Jy

foreach (GridViewRow row in GridView1.Rows)
{
    if (row.RowType == DataControlRowType.DataRow)
    {
        CheckBox chkRow = (row.Cells[0].FindControl("Transfer_Selector") as CheckBox);
        if (chkRow.Checked)
        {
            //do something
        }
    }
}

It's runs fine when check-box is not checked.

And when check-box checked it's make loop in for-each fail again.

Anyone ever had a problem like me or know what's happened.