it IS in the guide, thats south of the Draynor Bank. Check the 3rd pic of the treasure trail guide: http://www.tip.it/runescape/?page=treasure_trails.htm
You have at least two pieces wrong, the middle on on the left column and the middle one on the rightmost column. Try looking on the tip.it Treasure Trail page for a pic of how its supposed to look.
I have a theory that only training one skill give you a better chance.. dont bury bones or id herbs etc... not sure whether its true, but i got my mimes doing this.
Fighting is the key to getting mimes... I suggest fighting in one spot for a looong time, go get some food, then go back and fight there... keep doing this for a few days and you should get a bunch of mimes.
Ice Warriors is a great spot to get mimes, friend of mine got 6 mimes there in 4 days. Just fight, fight, fight, go grab some more food, fight, fight, fight....
I might add that you only get Saradomin or Zamorak wizards when you dig at coordinates (except the one in duel arena), you never get wizards when you dig at map locations or riddle locations.