How do I make part number and quantity display the correct value in the correct textbox ?

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C#

I have made a manufacturing form and the goals when I scan it with a barcode reader it should appear in the text boxes corresponding to the barcodes. It will also manufacture parts. When I ran it, the EmpID corresponds with the barcode but doesn't display the Employee name. As soon as I scan the barcode for the Part Number "P" appeared in the text and "1-1" appeared in the quantity textbox which it shouldn't then a message saying input string is not in the correct format.

this is my code:

private void txtEmpID_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar == (char)Keys.Enter)
    {
        txtPartNumber.Focus();
    }
}

private void txtPartNumber_KeyPress(object sender, KeyPressEventArgs e)
{
    txtQuantity.Focus();
}

private void txtQuantity_KeyPress(object sender, KeyPressEventArgs e)
{
    try
    {
        if (e.KeyChar == (char)Keys.Enter)
        {
            SQLInventoryClass MySQL = new SQLInventoryClass();
            int Quantity = int.Parse(txtQuantity.Text);
            lb1PartName.Text = MySQL.GetPartName(txtPartNumber.Text);
            if (txtPartNumber.Text == "p1-1" || txtPartNumber.Text == "p1-2" || txtPartNumber.Text == "p1-3" || txtPartNumber.Text == "p1-4")
            {
                MySQL.AddInventory(txtPartNumber.Text, 
                                  Int32.Parse(txtQuantity.Text), 
                                  txtEmpID.Text);
                lb1Status.Text = txtPartNumber.Text + " added ";
            }
            // Manufacture a p2-1
            else if (txtPartNumber.Text == "p2-1")
            {
                int numPart1 = MySQL.GetQuantity("p1-1");
                int numPart2 = MySQL.GetQuantity("p2-1");
                if  (numPart1 >= Quantity && numPart2 >= Quantity * 2)
                {
                    MySQL.RemoveInventory("p1-1", 1 * Quantity, txtEmpID.Text);
                    MySQL.RemoveInventory("p1-2", 2 * Quantity, txtEmpID.Text);
                    MySQL.AddInventory("p2-1", 1 * Quantity, txtEmpID.Text);
                    lb1Status.Text = "Quantity of " + txtQuantity.Text + " added with part number " + txtPartNumber.Text;
                    txtEmpID.Text = "";
                    txtPartNumber.Text = "";
                    txtQuantity.Text = "";
                    txtEmpID.Focus();
                }
                else
                {
                    lb1Status.Text = "Error: not enough parts in inventory of manufacture parts.";
                }
            }
        }
    }
    catch (Exception ex)
    {
        MessageBox.Show(ex.Message);
    }
}

What I have tried:

I have tried googling the problem, I emailed my instructor early but receive no response. I used the debugger and went in step over the code.