VALIDATION USING VALIDATECHILDREN(), VALIDATING(), VALIDATED() AND ERRORPROVIDER NOT TALKING TO ONE ANOTHER

I am validating user inputs using the above-mentioned functionality.

but when i press the ok / insert button this this.ValidateChildren(ValidationConstraints.Enabled)always return true.

below is my code.  Kindly help . I am new to c# and dotnet.

 private void textBox2_Validating(object sender, CancelEventArgs e)
        {
            bool cancel = false;
            int number = -1;
            if (int.TryParse(this.textBox2.Text, out number))
            {
                if (number>0 && number<100)
                {
                    //This control passes validation.
                    cancel = false;
                }
                else
                {
                    //This control has failed validation: number is not in the correct format
                    cancel = true;
                    this.errorProvider1.SetError(this.textBox2, "You must provide a number wit the format 11ddd!");
                }
            }
            else
            {
                //This control has failed validation: text box is not a number
                cancel = true;
                this.errorProvider1.SetError(this.textBox2, "You must provide a valid number!");
            }
            e.Cancel=cancel;
        }
        private void textBox2_Validated(object sender, EventArgs e)
        {
            //Control has validated, clear any error message.
            this.errorProvider1.SetError(this.textBox2, string.Empty);
        } 





private void button2_Click(object sender, EventArgs e)
        {

            
            if (this.ValidateChildren(ValidationConstraints.Enabled))
           // if (validateOfficeId())
            {
                SqlConnection con = new SqlConnection("Data Source=.;Initial Catalog=mOICISTAFF12;Integrated Security=True");
                SqlCommand com;
                con.Open();
                com = new SqlCommand("INSERT INTO offices VALUES('" + textBox2.Text.Trim() + "','" + textBox3.Text.Trim() + "','" + textBox4.Text.Trim() + "','" + textBox5.Text.Trim() + "','" + textBox6.Text.Trim() + "','" + textBox7.Text.Trim() + "')", con);
                com.ExecuteNonQuery();

                //MessageBox.Show("i am in the validatechildren");
                textBox2.Text = string.Empty;
                textBox3.Text = string.Empty;
                textBox4.Text = string.Empty;
                textBox5.Text = string.Empty;
                textBox6.Text = string.Empty;
                textBox7.Text = string.Empty;
            }
            else
            {
                MessageBox.Show("there are invalid controls on the form");
                Form1_Load( sender,  e);
            }