Squid and FTP Upload

[Phibee Network Operation Center <noc@xxxxxxxxxx>]

Hi

i use squid for my user and i have a small problems:

A user want access to a FTP server with IE. He use the
url ftp://login:pass@xxxxxxxxxx

He can see the ftp, see all files but if he want upload a file, he have 
a error
msg that said: "Your proxy are not configured for ..."

My squid don't are configurerd for relay the upload ?

thanks
jerome