10 speed cassette/derailleur, but only getting 8 clicks?
If you are skipping gears, I suggest the cable tension need to be reset. Shift to the smallest cog, undo the bolt fastening the derailleur cable and then refasten, ensuring there is just enough tension to hold the cable tight. You should then be able to accurately shift up one gear at a time and go through all 9 clicks. It may take a few attempt to get right, and you should test it with different front gears selected. Also check for worn cable or housings.

Looks like you need to set the limit adjuster also, there are two small Philips head screws that do this. They prevent the derailleur shifting past the largest and smallest sprockets.