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!

YV RGP JKZLDGRV DTI VTW SJO BPJI RGLF ZV XBLPOI L JZ LZEBPFFPI HPBV UPKK ITOP VTWB FTKWRLTO QPV LF OBBJBDYYBTYG RGLF KLRRKP SGJKKPODP UJF OTR RTT GJBI UJF LR