weired ProFtpd error: 550 Overwrite permission denied !!
 

Hello All.
I have RH 9 server with whm 9.4 installed and proftpd as ftp daemon.Recently one of my client complained that he can't edit the files in his account.
What he was doing is download the file ,make changes then upload and then he got error
550 :/ Overwrite permission denied
I have checked the permisions of files in his folder .They are 755,with owner and group etc correct .
I even checked the permissions of public_html folder it is 777.
Why it is not allowing the use to edit file even he has permissions to do so.
All other domain on server are n't having this problem ..but only this one is showing up problem.
One more interestiung thing is that I can edit the same file from cpanel file manager and save it successfully, but same process halts when I try it from ftp client software!!
Any hint?

do an ls -l of the files, is there a `t' at the end of the permissions? if so that'll be the sticky bit which might be inhibiting it.