strange error when trying to connect

this is what I receive and I can't explain why the 2nd line with my site information is all in caps...
can someone help me, pls.?
thanks in advance
cheers, anja

Connecting to x.x.x.x Port: 21
Connected to mysite.com.
220 x.x.x.x FTP server ready
SITE my-site.com
500 'SITE MY-SITE.COM' not understood
QUIT
221 Goodbye.
Cannot login waiting to retry (30s)...