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!

NZ APD BKTGWPAZ WOV ZOS UBC IDBV APGQ TZ JIGDCV G BT GTHIDQQDV XDIZ YDKK VOCD ZOSI QOKSAGOC LDZ GQ CIIBIWNNIONP APGQ KGAAKD UPBKKDCWD YBQ COA AOO PBIV YBQ GA