CakePHP Master/Detail Form - simple Issue

I'm building a simple master/detail edit form using Cake, but can't get the values from the details records to populate the form.

Workorder -> Master WorkorderIssues -> Detail

DebugKit tells me the data is being returned properly from both the master and detail tables.

I can populate the form with master data just fine using:

Form->input('workorder_ref');?>

..but the same approach doesn't work for the detail data:

Form->input('WorkorderIssues.issue_owner');?>

Post data:

Workorder(array) workorder_id 1 workorder_ref 9212

WorkorderIssues(array) 0(array) issue_id 1 issue_workorder_id 1 issue_owner shaun

I would appreciate some help..it's probably something simple I'm overlooking.

Many Thanks, Shaun