This sounds odd, i'm sure it works for me - which version of Tiki are you using?
Have you thought about filing a bug report on File a bug? Then you can create a "show" tiki to recreate your issue which sometimes solves the problem in itself, and if not gives us devs a clean example of the problem so we might fix it.
By the way, i presume your example says field instead of fileId due to some autocorrect thing?
Thanks for the question, hope we can get it sorted out for you!