exists(file on my computer) not doing very well

[Richmond]

In a card of my upcoming "Grendel" for Anglo-Saxon, Gothic and other warped
Germanic languages/writing-systems I have this script:

on preOpenCard
    set the title of stack "grendel" to the short name of this card
    if exists(url("file:" & "GrendelBackUp.rtf")) then
       put "exists"
       set the RTFText of fld "store" to URL ("file:" & "GrendelBackUp.rtf")
    else
       put "nope"
       end if
end preOpenCard

Now the file GrendelBackUp.rtf is present where I saved it earlier, from 
the stack,
in the default folder.

So would be glad if somebody could tell me why I keep getting "nope" in 
my Message Box.

Richmond.