Image Upload Naming

I am working on a real estate system.
I'm needing uploaded images to follow an incremental naming system of propertyID_imagenumber.jpg

So, for its propertyID 51 I would hope to get:

51_1.jpg
51_2.jpg
51_3.jpg

What I'm getting, although amusing, is not what I had in mind:

51_[Increment].jpg

In the file name box on the wizzard I have:
<?php echo ((isset($_POST["propertyID"]))?$_POST["propertyID"]:""); ?>_[Increment]

Which gives me:
'FileName' => "".((isset($_POST["propertyID"]))?$_POST["propertyID"]:"") ."_[Increment]",

What am I doing wrong please?

the File Name setting wont take the [Increment] Command, you can only use that in the first page in the If file exists section.


in the If file exists section, set it to rename the new file using the default [FileName]_[Increment] setting.

in the second step, only use the property ID form element binding, with out adding the [Increment]:
'FileName' => "".((isset($_POST["propertyID"]))?$_POST["propertyID"]:"") ."",

This wont be 100% what you are after, the first image will be named:
51.jpg

but further images will be named:
51_1.jpg
51_2.jpg
51_3.jpg

Almost...

The first file originally called P1010655 gets renamed 51.jpg.

Subsequent files get named:
P1010656_1.jpg
P1010657_1.jpg
P1010658_1.jpg

I guess I should give up on file renaming, its not going to give the results I was hoping for.
I would be better off finding a way of inserting the original file name and propertyID into a database, once the upload is complete and let the database worry about file names.
Is there an easy way to call the file name after the upload?

  Is there an easy way to call the file name after the upload?  

the file upload behavior creates a binding group on the bindings panel called WA Uploaded Files (File Field Name) this binding group contains a binding called "Server File Name that is the name of the uploaded file.