Multi-criteria search Functionality to your Access application ?#

Error:

System. ArgumentException: "This list cannot be cleared."

Code:

private void button3_Click(object sender, EventArgs e)
{
if ((textBox2.Text != "") ||
(textBox3.Text != "") ||
(textBox4.Text != "") ||
(textBox5.Text != "") ||
(textBox10.Text != "") ||
(textBox8.Text != ""))
{
if (radioButton1.Checked == false & radioButton2.Checked == false) { radioButton1.Checked = true; }
dataGridView1.Rows.Clear();
string type = "";
string name = "";
string weight = "";
string company = "";
string client = "";
string price = "";
string log = "";
int y = 0;
if (radioButton2.Checked == true) { log = "OR "; }
if (radioButton1.Checked == true) { log = "AND "; }
if (textBox2.Text != "")
{
type = "??? = '" + textBox2.Text + "'"; y = 1;
}
if (textBox3.Text != "")
{
if (y == 1) { name = "" + log + "???????????? = '" + textBox4.Text + "'"; } else { name = "???????????? = '" + textBox4.Text + "'"; y = 1; }
}
if (textBox3.Text != "")
{
if (y == 1) { weight = "" + log + "??? = " + textBox4.Text + ""; } else { weight = "??? = " + textBox4.Text + ""; y = 1; }
}
if (textBox5.Text != "")
{
if (y == 1) { company = "" + log + "????? = '" + textBox5.Text + "'"; } else { company = "????? = '" + textBox5.Text + "'"; y = 1; }
}
if (textBox10.Text != "")
{
if (y == 1) { client = "" + log + "?????????? = '" + textBox10.Text + "'"; } else { client = "?????????? = '" + textBox10.Text + "'"; y = 1; }
}
if (textBox8.Text != "")
{
if (y == 1) { price = "" + log + "???? = " + textBox8.Text + ""; } else { price = "???? = " + textBox8.Text + ""; y = 1; }
}
string query = "SELECT ???, ????????????, ???, ?????, ??????????, ???? FROM ??????? WHERE " + type + name + weight + company + client + price + "";
Form2 form2 = new Form2();
OleDbCommand command = new OleDbCommand(query, form2.Connection);
OleDbDataReader reader = command.ExecuteReader();
while (reader.Read())
{
dataGridView1.Rows.Add(
reader[0].ToString(),
reader[1].ToString(),
reader[2].ToString(),
reader[3].ToString(),
reader[4].ToString(),
reader[5].ToString());
}
reader.Close();
}
else
{
MessageBox.Show("?? ?????? ?? ?????!");
}
}