make a commit after checkout

Hi, I make a checkout from a project on our server (via FTP)
1- I have done some changes, when I run "bzr commit " and enter FTPserver pass, I face this error:

bzr: ERROR: Cannot lock LockDir(ftp://user1@[IP}/my.repo/my.main/.bzr/branch/lock): File exists: '/my.repo/my.main/.bzr/branch/lock/dgfe1u6ayq.tmp': 550 Create directory operation failed.

I think there is a permission error :-? What do you suggest? How do I solve it?

2- When I try "bzr update" it replace all the FTP server files on my project!!!! and I lost my changes :(
What does updateexactly done???!!!!!