Trying to verify a null text field

I'm using this script to verify the text field. The sting in my application shows the empty field as "" (two quotes)

[ ] Boolean bbFindText = Browser.Documents0Of0ListView.TextExists("")
[-] if bbFindText == TRUE
[ ] WriteSuccess ("*** TaskSpec1 DID NOT update --- PASS")
[-] else
[ ] WriteWarning ("TaskSpec1 updated to BBB --- FAILED")

The resultfile prints "Error-test failed to complete: The text parameter must not be empty."

I'm searching, but I can't figure out what I need to put between the quotes so that SilkTest views it as null.