FTP .... empty files uploaded

I can connect through FTP login process fine... I run into a problem when I am transfering my files... It appears that the files have been transfered using the STOR procedure... but when I open up the file on the transfered site... the file is empty (file size 0)... Does anyone know what is happening??? Does this have to do with the Data channel and Control Channel... I am not to savy about FTP... Any help would be appreciated Thanks, Veronica