@ella_s I'm not sure what is causing your issue.I was able to reproduce your error with the workspace you attached.I deleted your writer and then used Writer -> Import Feature Type to import a new waypoint feature type from an existing .ov2 file, that I created using thePoiEdittool (I've also attached that .ov2 file)
We'll take a closer look at why your workspace failed.In the meantime this should get you moving forward.
Requirements for using the FME TomTom POI reader/writer are in the TomTom POI reader / writerdocumentation.