depending on what films they are holding in their port, will determine how the fund does. Also, sometimes fund managers may be busy with real life situations, and cannot pay all the attention to the fund that is needed.
If you feel the fund is a good buy, then why not purchase some shares? This will also give you an idea of how the fund is doing, or you may want to buy a "radar" share (1 share only) and watch that fund's movement.
Just like any security, Funds go up or down depending on their holdings...it's market forces at work. 