lun snapshot not possible

on one of the luns I am getting a lun snapshot not possible.

100GB       85GB       14GB      85%

is it because I dont have enought space?

lun snapshot not possible

If a LUN has Space Reservation enabled and Fractional Reserve in the containing volume is set to 100% then the volume must have at least the size of the LUN available as free space or snapshot creation will fail.

I suggest you have a read through the info on Space Management here: