[REBOL] Error explanation

[ptretter]

Please explain this error I get:

** Script Error: val needs a value.
** Where: val: first params switch/default type?/word

I get the above error when executing this script I created:

REBOL []

ftpaccess: layout [

    backdrop 0.128.0 title "Pauls FTP Access" 255.255.0
    
    text "Enter Host Address/Directory" hr: field "127.0.0.1"
    text "Login Name" ln: field "administrator"
    text "Password" Pw: field "testpwd"
        
   button "FTP Access" [
       ftpurl: join ftp:// [ln/text ":" pw/text "@" hr/text]
       data: read ftpurl
       view layout [
       text "Directory contents:"
       area print data       
        ]
       ]

view ftpaccess