[chirp_users] CHIRP and BF-F9 not write with an error, why?

hi just programmed my Pofung BF-F9 (like an UV-5R )..... with chirp

with no problems !

Today i READ all ok , but i think to WRITE into the radio , it say this error:

http://i65.tinypic.com/14bnngl.jpg

is the first time i see this error..... no problem before this day !!!

a Trick, if i end the chirp program, NOT read but direct WRITE ... chirp not say to me this error....why ?

thanks best 73