G'day Geoff,

Welcome to the Monastery.

As others have noted, you haven't provided sufficient information for us to provide a concrete solution. Having said that, this part looks wrong to me:

... ->pack(@pl), DisplayGroup();
[download]

Perhaps one of these two was intended:

... ->pack(@pl); DisplayGroup();
... ->pack(@pl, DisplayGroup());
[download]

[With respect to fixing the bogus link caused by use of 'pre' (instead of 'code') tags, see "Writeup Formatting Tips" and "How do I change/delete my post?".]