Oh dear, I guess you have cracked the two caesar cryptos...
This one is more difficult. Although a simple substitution is easily cracked...
Again the characters are limited to A-Z... But I think I can come up with a 256 version again.

Enjoy!

UT YHQ WGIEAHYT ALO TLV KWN SQWO YHEJ IT DSEQNO E WI EIZSQJJQO BQST PQGG OLNQ TLVS JLGVYELN FQT EJ NSSWSAUUSLUH YHEJ GEYYGQ KHWGGQNAQ PWJ NLY YLL HWSO PWJ EY