[AS2] Problem attaching several MCs in Flash 6

Hi all,
Im targetting Flash Player 6 users and the trouble I found is that while using attachMovie function I cant attach all the MCs I want in same frame for some reason, I know its because of Flash version since changing the configuration to Flash Player 7 makes it work perfect.

Im running 2 for loops nested and attaching some tiles within them, I have noticed that only seems to attach one MC which happens to be just the last one.

My current configuration is that every MC is in frame 2 and with the option to load them on 1st frame disabled, in 1st frame is my preloader, I run the main code on frame 3. I have tried changing those options too but none of my tries seems to work, and Im sure attachMovie is supported by Flash 6 and AS2 as seen in the documentation.

Many thanks for any ideas or suggestions.