Why do I still get error code returns even the file uploads by sftp to window server succesfully?

Dear Expert,

When I tried to upload the file from unix machine to remote window ftp server in Perl script, my perl script dies since the code catches the $CHILD_ERROR with value 1536 from the system call even the file is transfered to the ftp server completely.  

Then I tried to do the same thing from the unix command line, and the following is what I have:

I am using public key authorization.
>sftp user@serveraddress
GlobalSCAPE Secure FTP Server * UNREGISTERED COPY *
sftp> put test.txt
test.txt                      |  238B |  238B/s | TOC: 00:00:01 | 100%
chmod_dest_before_transfer: ././test.txt (dst): no such file (server msg: 'File not found')

The first line tells us that the file is transfered completely. But I don't know what the second line means, and I am suspecting that the error caught in the script is from this second line.

Could anyone help on this?

Thansk,
Hanqian