i need to use the Trim Activity feature, but its not allowing me to. I started on my bike ride and forgot to start my activity. I know exactly what time I started and what time I ended from another GPS program. But really I need to copy the route map from my way to the location since I did the same route back, and create a new start, end, and total time. But I can't. I thought this was the whole point of the Trim Activity feature.