Questions about a Zelkova Serrata - Beginner 2nd Year

I purchased a Zelkova Serrata in the Spring of 2013 and re-potted it this spring. All but 5 of the buds have yet to pop on it and it is the middle of May. I live in Alabama and everything else is green. I don't believe it is dead because it does have 5 leaves on it and I have removed a few buds in other locations on the tree and while they haven't popped yet, they are green underneath them and inside them. Is there any reason why the tree hasn't leafed out yet? Do I just need to be patient and it will eventually turn green sometime this summer? Any advise or suggestions would be greatly appreciated! Thanks!

Where are you keeping the tree? Trees are sometimes a bit slow responding in a repotting year. How many roots did you remove? Loss of a significant (more than 30%) number of the roots will also slow down growth. Have you fertilized?