Array Problem

in the main file, i create an array named Q4 for 40 item, so it is Q4[0] to Q4[39], then i use attachmovie to insert few movie clips (using looping), this movie clips name is ‘pass’ + i. i need to read the value of the array from the ‘pass+i’ movie clip, but it doesnt work, this is the code

ctn=random(40);
_global.Q4[ctn] += 1;

any idea of it? everytime the ctn repeat the same number, i need to add one (1) in the same array, e.g if Q4[1] appear for 3 time, then the value for Q4[1] = 3. Thanks for reply…