Hmmm I believe you don't need to place the "exact" number of a type of element in order to do alchemy (since it'll just grab the required amount for fusing). What is important is that you have enough of that type of element (to meet the requirement) but the "right" element level... check if you're using the right element level

maybe the requirement is 122 of lvl2 water and you've placed 200 of lvl1 water
Checkout this alchemy guide
http://www.silkroadforums.com/viewtopic.php?t=12542