Hi Ben,

As of now, in AFNI, there is no difference between a functional
dataset and an anatomical one. There was a difference (a small
one) up to a few weeks ago.

In any case, you must choose your 3d+time dataset as the
anatomical underlay in order to use the Graph window.

In the past, a functional dataset was one that came from some
computation (e.g. a statistical output dataset), while an
anatomical dataset was one that was based on (perhaps warped
or resampled) raw data (e.g. an SPGR dataset, or an EPI 3d+time
dataset).

If you are using an older version of afni, you will not be able to
select a 3d+time "anatomical" dataset as the functional overlay.
You could use "3drefit -fbuc -prefix new_dset old3dtime+orig" to
tell afni to consider it as a functional dataset, but changing it
to a bucket dataset may cause you some other problems.

At any rate, just update your AFNI distribution. That will enable
you to choose any dataset as the anat underlay, and any as the
func overlay. Though again, you need to select the dataset as an
anatomical underlay in order to view it in the Graph window.

- rick