You’re missing a overlay!
&overlay FIRE1 opacity 1 in 0 THEN overlay FIRE1 opacity 1 in 0.1 THEN overlay FIRE1 opacity 0 in 0 THEN overlay FIRE2 opacity 1 in 0 THEN overlay FIRE2 opacity 1 in 0.1 THEN overlay FIRE2 opacity 0 in 0 THEN overlay FIRE3 opacity 1 in 0 THEN overlay FIRE3 opacity 1 in 0.1 THEN opacity FIRE3 opacity 0 in 0 loop INFINITE times <— one overlay missing and one opacity to much.
Ps: Sorry, that was my misstake. As I said my computer was lagging. Even crashed soon after…