Because too many of your recent edits have been rejected; see 1,2,3,4,5.
Reviewers often rejected your edits for "This edit is incorrect or an attempt to reply to or comment on the existing post". Looks like the edit you made are changing the meaning and that is something that is not wanted on the site.
Maybe you should comment on post rather than try to edit them sometimes.
I'm not saying you made only bad edits but sometimes, you should choose posts where there are a lot to improve rather than just a word or a sentence. This will help reduce the rate of rejection for too minor. Also, if you see that you change a lot of words (to rephrase stuff better), it might be a good idea to make longer comments on the edit to show that you didn't change the meaning, but only rephrase.
Also by pressing the more link on an edit you can see your stats (which are currently 24 accepted and 12 refused).