attach movieclip doesn't work

I'm trying to change a movieclip when clicking on a button, i have done this many times in this scene but this one doesnt seem to work and I'm out of ideas.

this is image a significantly simplified version of what im working on

http://i.imgur.com/4HyIAhh.png

-actionscript 2.0
-flash 8

frame 1 CODE:

Code:

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var activate = 0;

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set var CODE:

Code:

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on (release) {    var activate = 1; }

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check var/ change mc CODE:

Code:

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on (release) {    if (activate == 1) {    options_modified_mc_INST.attachMovie("options_modified_mc_1_INST", "options_modified_mc_1_INST", this.getNextHighestDepth());    } }

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this is costing me a lot of time already, please help me out if you know why it's not working