Need help with a simple code

ok, i'm working on a project for my studies, where i have to make an interface for a cell/touch phone. for one part of my menus (the sub-sub menu) i've placed the buttons onto a MovieClip and made left and right buttons, which should move them a certain amount of space in either direction. my problem now is that i want them to stop moving the MC when it's at it's end, otherwise there will be nothin displayed, and that would create some confusion in the user. i tried using a for loop, but it won't work. i'm not the best when it comes to scripting, and AS is really new to me, so i dunno what's wrong. the output window tells me this when i check the code for errors:



edit: this problem is solved, but my code still won't do what it'd like it to do. any ideas?
**Error** Symbol=inbox_menu, layer=actions, frame=1:Line 1: Operator '=' must be followed by an operand
for(i=0; i=<689.8; i++){

**Error** Symbol=inbox_menu, layer=actions, frame=1:Line 10: Operator '=' must be followed by an operand
for(i=689.8; i=>0; i--){

Total ActionScript Errors: 2 Reported Errors: 2

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here's the code i made (689.8 is the width of the movieclip the buttons are on):


for(i=0; i=<689.8; i++){

arrow_btn_left.onRelease= function()
{
inbox_mc._x=inbox_mc._x +223;

}
}

for(i=689.8; i=>0; i--){

arrow_btn_right.onRelease = function()
{
inbox_mc._x=inbox_mc._x -223;

}
}

----

here is the faulty version of the .swf file, in case you want to take a look at what i mean, cuz i have the feeling i explained it a little confusingly.