Lets see if I have everything clear.
Your island PBO file is called .....mayfield.pbo
Your .wrp file is called ...............mayfield.wrp
The displayed name in the island selection list is .........mayfield.
Your icon for display in the island selection list is called ......mayfield.paa, and is located in your island PBO, so the path is ...........\mayfield\mayfield.paa.
I'm not sure about the cutscenes declaration though, doubt it would cause it not to work.......lose it anyway.
If all else fails, send me a copy of your island and I will see if I can get it ingame.
mcnicoll7@yahoo.com
Planck