delays and margin compression

My guess is that there has been major delays to revenue due to the floods which has caused a problem.
They had already flagged in nov 2010 that their revenues would be "heavily skewed" ie 35% H1 vs 65% H2 . obviously this creates a cash flow problem. Remember Nov was before the major floods had occured, so presumably their revenue has been further pushed out, and so exacerbating the problem.

They also flagged some margin compression flowing through from the GFC deals.

I suspect that this all adds up to nervous bankers, who will want no dividend paid for starters.
Having been asked to hold fire on covenants till march31 (in NOV management would have hoped that things were starting to look clearer revenue wise, but instead they have had further delays!)
Bankers being what they are, will be putting very strenuos conditions on any further extensions, such that HST will be thinking the lesser of 2 evils will be a cap raising.
A 20-30m cap raising will add about 8% to equity, so not a major dilution but it will buy some time, time for the delayed revenues to flow through, time for their full order book to flow through.
With all the flood rebuilding and resurgent mining expenditure there will be a fair amount of work around and margins should recover strongly.