Importing a simple custom string attribute from bugzilla

After reading "TN0007: Guide for Importing Jazz Work Items from Bugzilla and Other Systems" i've managed to define two enumerators and import these enumerated attributes from a bugzilla bug into a RTC defect.

i can't however figure out how to define the mapping for a simple custom string.

I added this in my mapping xml

<attribute sourceId="status_whiteboard" targetId="whiteboard"/>

and this in my process configuration source

<customAttribute id="whiteboard" name="whiteboard" type="smallString"/>
<presentation attributeId="whiteboard" id="whiteboard" kind="com.ibm.team.workitem.kind.string"/>

but the status_whiteboard attribute contents does not appear in the imported defects whiteboard field.

I'm probably missing something very simple... but can't wsee what

All help gratefully received
John