Web Forms :: Form Not Refreshing?

I am searching for a customer and displaying results on the same form. Now for some reason even If I am searching using correct format of the data the system is showing some predefined error messages. This measn that my previous error message is not refreshing.

This is the code:

if (txtANumber.Text.Length == 0 && txtBNumber.Text.Length == 0 && txtCNumber.Text.Length == 0 && txtDNumber.Text.Length == 0 && txtLastName.Text.Length == 0 && txtFirstName.Text.Length == 0 && txtDOB.Text.Length == 0)
{
GridViewCustomers.DataSource = null;
GridViewCustomers.DataBind();
lblNoResultsMsg.Text = "Please enter search details";
lblNoResultsMsg.Visible = true;
valid=false;
}
else
{
if (errors== 0)
{
GridViewCustomers.DataSource = null;
GridViewCustomers.DataBind();
lblNoResultsMsg.Text = "Please enter correct format of A Number ";
lblNoResultsMsg.Visible = true;
valid = false;
}
else if (errors== 2)
{
GridViewCustomers.DataSource = null;
GridViewCustomers.DataBind();
lblNoResultsMsg.Text = "Please enter correct format of B Number ";
lblNoResultsMsg.Visible = true;
valid=false;
}
else if (errors== 3)
{
GridViewCustomers.DataSource = null;
GridViewCustomers.DataBind();
lblNoResultsMsg.Text = "Please enter correct format of C Number ";
lblNoResultsMsg.Visible = true;
valid=false;
}
else if (errors == 4)
{
GridViewCustomers.DataSource = null;
GridViewCustomers.DataBind();
lblNoResultsMsg.Text = "Please enter correct format of Date of Birth ";
lblNoResultsMsg.Visible = true;
valid = false;
}
else if (errors == 5)
{
GridViewCustomers.DataSource = null;
GridViewCustomers.DataBind();
lblNoResultsMsg.Text = "You need to search by FirstName LastName and DOB ";
lblNoResultsMsg.Visible = true;
valid = false;
}
else if (errors == 6)
{
GridViewCustomers.DataSource = null;
GridViewCustomers.DataBind();
lblNoResultsMsg.Text = "Try Again";
lblNoResultsMsg.Visible = true;
valid = false;
}
else
{
valid = true;
}
}