Managed Properties in FAST 2010 Search Server
Is there a difference between creating Managed Properties between SharePoint 2010 Search and FAST 2010 Search?
The answer here is: Yes… the process of making a property searchable is a bit different between FAST and SP Search.
FAST can only filter/property search on Managed Properties. Managed Properties are derived from crawled properties and are not automatically created like in SP Search.
FAST does come with some default Managed Properties like Author, Site, Name, etc… and that’s why those properties work on you FAST system and not the newly created “Reference No”.
Here are the instructions on how to list/add/edit a Managed Property in FAST.
Try creating a managed property for your fields, recrawl, test searching on that managed property.