Varible problem when adding

Hey guys whats up this is a problem that would help a lot of people since it happens frequently

When I making a tetris game and everything done excpect I have a problem adding vaules to the score when I use this code…

The name of the varible is score
[COLOR=Red]
_parent.scores = _parent.scores - 500

[COLOR=Black][COLOR=Blue]I get “-500”, then “-1000”, then “-1500”[/COLOR]

sound correct right?

but when I use this code:
[/COLOR]
[/COLOR][COLOR=Red]_parent.scores = _parent.scores + 500
[COLOR=Blue]
I get “500”, “500500”, “500500500”[/COLOR]

[COLOR=Black]This code is in a onclip handler so when something collides it triggers this code to run, on a button it will work fine and add. >_<
So does anybody know if there is a way to fix this problem or force flash to reconize Im adding numbers?

For now Im using the work around solution, I put the score on -1000000 hide the “-1” give the illusion your actually getting points but I want to add high scores to my server so I must find a way out of this glitch. Here’s how the code looks like too if your wondering.

if(_parent.b001.box and
_parent.b002.box and
_parent.b003.box and
_parent.b004.box and
_parent.b005.box and
_parent.b006.box and
_parent.b007.box and
_parent.b008.box and
_parent.b009.box and _parent.b010.box.hitTest(this.lcq)){this.play();_parent.lineu++;_parent.lines++;
if(_parent.lineu==1){_parent.scores=_parent.scores-100;_root.gotoAndPlay(8)};
if(_parent.lineu==2){_parent.scores=_parent.scores-300;_root.gotoAndPlay(6)};
if(_parent.lineu==3){_parent.scores=_parent.scores-500;_root.gotoAndPlay(4)};
if(_parent.lineu==4){_parent.scores=_parent.scores-1600;_root.gotoAndPlay(2)};}

Dont worry about missing spaces I formated the code so it readable here so I’m 100% sure I have all spaces in the code. What happens here "Icq is a box that reads when 10 blocks touch each other (which is when you make a line in tetris) and from at the end starts adding the points. I showing the code because maybe since this is on a onclip event and not an on press event (which the adding did work on a button) maybe that has to do with the glitch.

I apoligize in the future if this has been solved already in another post I couldnt find it anywhere.

Thank you for your time.

Oh yeah and if your thinking about it, no, this game is not ripped from a tutorial I start it from scratch running on nothing but movieclips and varibles and hittest.[/COLOR][/COLOR]