Dynamic text decrease / increase?

Hi friends,
I wanna consult you something about.
I have a Dynamic Text area called txt, I write the value 5000 by txt.text=“5000”;
In my scene there will be 2 buttons. When one of the buttons is pushed the value will decrease 250 by 250. For example; at first push it will decrease to 4750, at the second push it will decrease to 4500 and so on…And when it is pushed to the other button this value will increase 250 by 250. For example; the value will be:4500 by pushing twice to the decreasing button, then it’ll be:4750 by pushing once to the increasing button.
I tried with the below codes but it didn’t work. The value decreases only once, it doesn’t keep on decreasing when I pushed twice to the decreasing button.The value seems as 5000250.

txt1 = txt.text;
Decrease.onRelease = function() {
txt.text = txt1 - “250”;
};
Increase.onRelease = function() {
txt.text = txt1 + “250”;
};
And there is one thing too I wanna make if it is possible; I want to place the decreased value of txt dynamic text to valuetxt dynamic text. For example; when the value is done as 4500 by pushing twice to the decraesing button, the valuetxt area will be 500. When the increasing button is pushed once, txt value will be 4750 and valuetxt area will be 250.

I have to do it by AS2.
I have no idea how I’ll make its coding. I searched very much but couldn’t. It’ll be so nice if you can help me by sample files.
Thank you so much for your kind help.