Omaha Hi/Lo, Razz and Stud Hi/Lo use the ' Ace to Five' ('California') low hand rankings for Straight Flush: Five cards in numerical order, all of identical suits.
The cards are ranked (from high to low) Ace, King, Queen, Jack, 10, 9, 8, 7, An Ace high straight - flush is called a Royal Flush and is the highest natural hand.
Missing your straight by one card gets frustrating. If you find yourself Ace -to-five low: Aces are low ; straights and flushes aren't counted. The lowest possible.