Dave,
Where are you calling from? If outside the US, you may have to set
some of your local parameters to allow binary file transfers. For example, in
Canada, you have to make some changes to the DataPak settings for them to work.
If inside the US, that shouldn't be a problem, so the next thing is to
let us know which terminal program you're using. Some have to be set to 8
bits, no parity, 1 stop bit before the transfer for it to work.
Finally, make sure your serial preferences (using the program
Preferences) is set to NONE for it's handshake protocol.
Don