subform query

I am using ID# field as a combobox of unbound field in a form to
select and display related information shown at the subform, so a memo
field is warpping and readable, say, ID# would be a link field for
both master and child fields , however, in the Form design, I got
message from Subform field linker "--can't build a link between
unbound forms", anyone know any alternative to get around, or should
use other ways to retrieve record information but it needs be able to
show memo field in a wrapping text.

Thanks in advance for help.