Apparently the load factor on some of the newer routes they expanded into was well below 50%.
They got some capital from the state of Carinthia although they were almost bankrupt at the time and would have needed more capital (from more provinces) to continue operations. There was no political will to give that money and no (more) private investment either.
Probably just the wrong business model and aircraft at the wrong time. Very bad for the pilots, who had just elected their first works council. Even worse for those who left Lauda Air and Tyrolean for Styrian.