Try counting them again. 1 down and 5 up. Make sure you are moving fast enough to get it into the last gear. If just trying to do it at a stop, it is hard to go through all the gears. Once you are in first... it will only go UP 5 gears.
If still not.. change the oil and filter. Dirty oil can screw with shifting. Also make sure your clutch lever is properly adjusted with the correct amount of slack per the owners manual.