There is nothing wrong with the code. I did a UNIT TEST just to make sure. Try running the following and you will notice that it exits out and does not print when the

if($_ eq $img_name)

statement is reached.

@array = (0, 1, 2, 3, 4, 5);

foreach(@array){
    if($_ eq 3){
        last;
    }
    print "$_\n";
}

#this will output
#0
#1
#2
[download]

Try checking to make sure $img_name is what you think it is, or it may be that the defined $img_name is not contained within the file and therefore no match will be made?