Yes, if you don't set up your vram correctly, the enb functions will not work. First, go to Skyrim/enbseries.ini, right-click and click 'properties'. Make sure this file is not 'Read Only'. If it is, uncheck that and click ok. Next, find and open Skyrim/enblocal.ini, and change the following variables:
[MEMORY]
ReservedMemorySizeMb=256
VideoMemorySizeMb=2000
VideoMemorySizeMb: This should equal how much vram your video card has. You will want to set this to 1000. If this variable says 0, or anything higher than 1000, then enb will not work. ReservedMemorySizeMb: Many people suggest leaving this at 256. I'm not certain what it does, but just make sure that it's 256. Try this and let me know.