Trying to understand subroutines

I was told I could expand the space in events by using subroutines; however, their mechanics looked difficult to learn so I decided to stay away from them.
Now that I'm better at scripting I gave it a go but I can't seem to get the hang of it. Here's what I'm doing.

When you talk to Cyan after the phantom train departs, you wait (B5 05) then displays the "Cyan: ..." message and ends. I decided to start a subroutine there (replacing the B5 with B2 and so on). I went to free space located at 010118 (CA/FF18?), so I went with B2 18 FF 01 FE.

On CA/FF18 I wrote my code, ended it with FE and returned. As I was afraid the game freezes (game stays still forever, doesn't shut down) whenever I speak to Cyan instead of supposedly doing whatever it is on CA/FF18. I'm posting a picture of my WindHex, hoping you can help me figure out why this isn't working for me.



Thanks in advance.