value not changing

Hi,

In a webform I have two textBoxes. In a formload event I will retrieve some data from db and will assign it to textboxes as below

textBox1.Text=dr.getValue(0).ToString();   (Sachi)
textBox2.Text=dr.getValue(1).ToString();   (Vasista)

Now in a button click event I will make some correction in the same textbox and I will asign those values to two string variables as below

string Fname=textBox1.Text.ToString(); (Sachin)
string Lname=textBox2.Text .ToString(); (Vasishta)

but when I checked the values of these 2 string variables using breakpoint the values were not changed, it was showing the old values which were retrieved from the db.

Thanks