Inserting mail adress in new message

Hi,
I have set up 2 adress book in my Lotus 6.5, my priovate own and the
other from my company. Normally I use to write the namein the "to"
field, email adress or name cam up automatically from my work adress
bon, but I don not why now it just came those adress from my private
one.
There is some kind of setup in order to choose which adress book has
to be used?
Thanks a lot!