I tryed to glue some kenya tree and some mushrooms to a rock the next day they are off the rock not sure how much glue i need to use i just put a little on the rock and pushed it on. if some has a picture of how to do this it would help.
Using glue to attach any softie to a plug/disk/rubble will not work. The glue will not adhere to the flesh, like Kasei said.
The toothpick/rubberband method works sometimes. I find the better method is wedding veil wrapped loosely around the rock and rubberbanded on the back side works ok too. The best method I know of is putting a tupperware tub in the tank in a low flow area. Put a good amount of rubble/shells/disks or whatever in the tupperware. Put your frag in there and it'll attach itself to it's substrate of choice.