Searching Multiple rows in datagridview through button click

[vinutha b]

private void button1_Click(object sender, EventArgs e)
{
//
DataGridView dgview = new DataGridView();
//dataGridView1.RowCount=0;
try
{
for (int row = 0; row < dataGridView1.RowCount - 1; row++)
{

// dataGridView1.MultiSelect = false;

if (dataGridView1.Rows[row].Cells["Model"].Value.ToString().Substring(0,textBox1.Text.Length ) == textBox1.Text)
{
dataGridView1.Rows[row].Selected = true;
dataGridView1.Rows[row].Cells["column1"].Value = true;
// MessageBox.Show("data has been selected");
}
else
{
MessageBox.Show("data not found");
}
}
}
catch (Exception Error)
{
//MessageBox.Show("data not selected");
MessageBox.Show(Error.ToString());
}


}
i have above code ........... when i perform it shows exception has "index and length must refer to the same location within the string" i'm not getting what to do .... fresher to this application ........pls help me