FTP 550 error message, why?

[rmworldwide48]

I just signed up and activated an FTP account.
The FTP works fine, i get in quickly, but as soon as i want to upload the even smallest of HTMl or any other files it tells me:
550 Disk full - please upload later

why is this and how can i fix it to behave normally??

 

[Smith6612]

Stoli's disk is full at the moment. We are looking to see what the issue might be that is taking up all the disk space.