Weird things on a mc timeline control

I´ve worked on a flash movie on which abnormal things are going on ;
Simple timeline control commands are not recognized (despite of frames being correctly addressed , all with frame labels ).
Then I made up my mind to discard an almost ready mc and start from clicking NEW , remake all the work from nothing and realized that this time I could have more control of the mcs.
Now to my chagrin , :m: , it happens again:
I have placed this : loadMovie(“flash/erp_sistms_20.swf”,20); on the timeline of another movie loaded on level10; the mc does not load (can assure that the file is placed in the folder flash and when tested alone it runs perfectly);
Maybe some of you have already experienced something like this and could give a hint.

ps.: I am working @ 40 frames/s , as I have never done so I suspected that it could be something related to frame rate , then I reduced to 12 fps and experienced the same trouble