Adding dynamic dropdowns to a DataAssist page

The records I'm trying to insert each have an associated category and each category has sub-categories linked to it. I've set them up as 2 tables in my database ok. DataAssist has generated the page and I have inserted records to the database fine with the specified category but I need dynamic dropdowns to make the sub-category list repopulate when the category is changed.

I thought I had this cracked but however I amend the DataAssist generated page I cannot add the "populate list from behavior" which is always grayed out.

I would really appreciate being pointed in the right direction, thanks!

before you can add the populate list from array behavior, you need to first add the Create dynamic Array server behavior.

the work flow is:

-create the parent select list
-create the child select list
-create a recordset to return the categories
-create a recordset to return subcatagories
-Add parent list, populate it using categories recordset
-Add the Create Dynamic Array, this will use the subcategories recordset. Bind the pasrent ID, child ID and Child text values to the corresponding columns of the subcategories recordset
-add the Populate List from array behavior to the onchange event of the parent select list.

When I do the last step I get the following error (see Attachment). I can't add the behaviour to the parent list. Thnx for any help.

What extensions including the version numbers are installed?

Dreamweaver CS6 Advanced Conditional Region Aktiviert George Petrov 2.0.1
Advanced Layer Popup Aktiviert George Petrov 1.0.8
Design Extender Aktiviert WebAssist 1.1.1
Ajax DataGrid Aktiviert DMXzone.com 1.1.1
Advanced Multi Uploader Aktiviert DMXzone 1.0.4
DMXzone Supersized Aktiviert DMXzone.com 1.0.2
DMXzone Updater Aktiviert DMXzone.com 1.6.2
PHP Date and Time Aktiviert Kaosweaver 1.0.4
Lorem Ipsum Generator Aktiviert Paul Taylor - Technocurve 1.0.4
PVII Accordion Panel Magic Aktiviert A. Sparber, G. Jacobsen - PVII 1.0.3
PVII Accordion Panel Magic 2 Aktiviert A. Sparber, G. Jacobsen - PVII 2.2.0
PVII Accordion Panel Magic 3 Aktiviert A. Sparber, G. Jacobsen - PVII 3.1.9
PVII Accordion Panel Magic Update v1.0.8 Aktiviert A. Sparber, G. Jacobsen - PVII 1.0.8
PVII Lightshow Magic Aktiviert A. Sparber, G. Jacobsen - PVII 1.3.0
PVII Pop Menu Magic 2 Aktiviert A. Sparber, G. Jacobsen - PVII 1.5.2
PopMenu Magic by PVII Aktiviert A. Sparber, G. Jacobsen - PVII 1.0.6
TabBar Magic by PVII Aktiviert A. Sparber, G. Jacobsen - PVII 1.0.9
PVII TabPanel Magic Aktiviert A. Sparber, G. Jacobsen - PVII 1.1.1
PVII Tree Menu Magic 2 Aktiviert A. Sparber, G. Jacobsen - PVII 2.1.7
PVII Tree Menu Magic 3 Aktiviert A. Sparber, G. Jacobsen - PVII 3.1.3
PVII Tab Panel Magic 2 Aktiviert A. Sparber, G. Jacobsen - PVII 2.4.6
TreeMenu Magic by PVII Aktiviert A. Sparber, G. Jacobsen - PVII 2.8.1
PHP Server Formats Aktiviert J. Andres Cayon 1.3.1
Pure PHP File Upload Aktiviert George Petrov 2.1.12
Recordset Navigation Suite Aktiviert Thomas Muck 3.6.3
Simulated Nested Region Aktiviert Thomas Muck 1.0.1
Smart Mailer PHP Aktiviert George Petrov 1.0.9
Data Bridge Aktiviert WebAssist 1.1.3
eCart Aktiviert WebAssist 5.0.7
DMXzone Bootstrap Aktiviert DMXzone.com 1.0.1

what order did you install the web assist extensions?

make sure to install in the following order:

eCart
Data Bridge
Design Extender

I reinstalled all WA extensions and it works now. Thanks Jason.