There are a myriad of issues that could lead to a station not playing an artiste's song. However, the first issue that needs to be addressed (in the case of Trinidad) is the amount of local music that is played on the stations. Most of the stations in the country cater to an American flavor and only during the carnival season do they play any local music (calypso, Soca and chutney flavors).
OK, in Trinidad there is one consistent "total local radio station" and that is WACK Radio 901 Fm (http://www.wackradio901fm.com) and they too have issues with certain artists and songs not being played.
They really try to play as much of the new music but many songs fall through the crack. Here are some things to consider:
1. Payola is an issue with some stations. I am saying this not because I know for sure but it is a fact of life in the music industry and I don't this it is any different in Trinidad or the rest of the West Indies. Pay for pay is a reality!
2. Some stations don't have a list of songs on rotation and leave it to the on air personality to play the music. Some of these DJ's are limited with funding and their personal tastes will dictate whom they play.
3. The stations should have a music pool from which the DJ's can get the music to play
4. The artistes too need to go themselves or send someone to "drop off" their music (hey these are the islands of the Caribbean Ok). Just go to the station and present your music in person; sometimes you may find yourself on air introducing your music with the DJ.
5. Some stations play mostly Soca with limited Calypso; some are chutney based with limited Soca and minimal Calypso. Know the stations and what they push before laying blame at any station footsteps.
6. Internet radio is big... send your music to these people... most of the time they will play your music
7. Get your fans to call the station to ask for your music ... fans listening to the station is the lifeblood for advertising dollars earned by these entities. That goes for the internet stations too (more important for the more established ones).
8. Think outside of the box don't lay blame on anyone - go out there and get your music heard.
9. Soca Mafia? Maybe... but that means that people are paying for this to happen! It also means that it is the artists destroying each other (those who have the income to do it)
10. People are already tired of poor lyrics and repetitive rhythms. The new music is too robotic. They need to get back to musicians in the studio to present a better sound. Whether or not you agree the quality of the music (lyrics and music) has deteriorated!
11. Hey people want to hear Soca and much of the music being presented is not really Soca but masquerading under the banner of Soca!
12. Too much inter island pettiness (I noticed this on Islandmix.com where there is a hatred for Trinidad/Trinidadian culture).