Trigger for appending text to particular file repeatedly stops working

[Morgotron]

Hi all,

I've created a trigger to append text to a particular txt file. The
trigger starts out working fine, but inevitably stops working after a
while. The entry for the trigger still appears in my QS triggers list,
but the file that I want to append text to somehow becomes deselected.
That is, the trigger reads "(null) > Append Text > <?>", where the
name of the file should be in the (null) position. Any thoughts about
how to remedy this problem?

I'm running Snow Leopard with QS B57, and have no problems with any of
my other triggers.

Thanks!