ScriptFTP

I've been a superficial user of the app for a few months and I just started playing with the GETFILESIZE script. I get the following error:

**** GETFILESIZE Error #550: Cannot get remote file size of xpa_db_200901300202.zip.
***** The server said: SIZE not allowed in ASCII mode

***** Stopped


I'm assuming if I change to binary it may work. How can I change from ascii to binary?

Thanks