More than one things to do if-statement C#

Hi,

if (this.textBox1.Text == "username" && this.textBox2.Text == "password")

            button10.Enabled = true;
            button3.Enabled = true;
            button4.Enabled = true;
            button5.Enabled = true;
            button6.Enabled = true;
            button7.Enabled = true;
            button8.Enabled = true;

            else

            MessageBox.Show("Error");

VS gives an error by the else-statement ('invalid expression term else'). Simple question: Why? and how do I solve this?

Thanks.