winforms errorprovider will not work after programatically changing data values in textboxs

[Rousseau10]

Hi all,

WinForms errorProvider will not work after programmatically changing data values in textboxes
I tried ErrorProvider1.Clear() but did not help. If it is a UI change by user, there is no problem with ErrorProvider1.
I tested after program changes code that it still runs through the txtAPU_Validated(object sender, EventArgs e) code correctly.
But no invalid icon next to field(s) appears.

So this code is my 'long way around the barn' work-around,, I had to use a temporary work around using a Boolean variable to change of textbox.text data value was changed in code, then dragged on and using errorProvidor3.

private void txtAPU_Validated(object sender, EventArgs e)
{
    bool bTest = txtAPUIsValid(@"(?i)^\d[0-9]?.\d{0,3}$");
    if (!progChangedText)//A.R.S. 7-12-15 - bool to check if the program changed the code (not the User)
    {

        if (bTest == true)
        {
            this.errorProvider1.SetError(txtAPU, "Field must contain only numbers and a decimal point. " +
                                                 "Up to 2 numbers before decimal point and up to 3 numbers trailing it.");
        }
        else
        {
            this.errorProvider1.SetError(txtAPU, "");
        }
    }
    else
    {
        if (bTest == true)
        {
            this.errorProvider3.SetError(txtAPU, "Field must contain only numbers and a decimal point. " +
                                                 "Up to 2 numbers before decimal point and up to 3 numbers trailing it.");
        }
        else
        {
            this.errorProvider3.SetError(txtAPU, "");
        }
    }

private bool txtAPUIsValid(string _rgxPattern)
{
    bool testBool = true;
    RgxPattern = _rgxPattern;
    Regex x;
    x = new Regex(RgxPattern, RegexOptions.IgnorePatternWhitespace);

    if (x.IsMatch(txtAPU.Text))
    {
        return false;
    }
    return testBool;
}
}

Here is the code for one of the button controls that repopulates TextBox.Text values that causes ErrorProvider1 to stop working correctly.

private void btnResetOriginalData_Click(object sender, EventArgs e)
        {
            errorProvider1.Clear(); errorProvider2.Clear(); errorProvider3.Clear();
            int i = 0;
            foreach (Control ctl in this.tlpTextBoxes.Controls)
            {
                if (ctl is TextBox)
                {
                    TextBox textBox = (TextBox)ctl;//casting Control Type to textbox
                    textBox.ResetText();
                    textBox.Text = strListControlValues[i];
                    i++;
                }
            }
        }

Thanks for any Help!
Rousseau10