Pokemon emerald Vitamin bug?

Question

When I use any vitamin to rise any stat I can rise only 1 or 2 in every stat no matter what lv I am (i tried in many lv too example 16 23 37 40 and 50) even hp stat I can still only get 1 or 2 Omg, XD!. Some 1 said I can gain 10 stat boost per each time when consume it. How to get 10 stats boost per each time and why I still get only 1 or 2 ?

Answer 1

Vitamins only work for the first 100 EVs of a stat. Your Pokemon were partially trained already, so they had EVs already.