Using bonemeal, I can successfully grow grass.. (wooo..) but every time i try to force grow a tree, it does the sparkly green thing, but no tree forms.  I can't do it with single saplings, nor can I do it with a 2x2 planting of jungle saplings.  
  
Is this a forge setting that I can change? I dug around a lot in the config files and couldn't find anything.  
  
I only have a few mods running: 
pixelmon 
Forgebackup 
Dynmap 
  
  
Has anyone had this same issue? I tried searching the forums and google but to no avail. Thanks!