Concatenation problem in AS2.0. Cannot create dynamic names

Hi all

I have the following problem which could be something simple after all
I have a number of loader intsances (loader1, loader2, loader) which I will use to load pictures.

I tried to create a loop and run the command

for(var st=1,st<4,st++) {

The concatenation “loader+st” doesn’t seem to work. Is it not supported in AS2.0?
Is there a workaround?