Hi Tracy,

When using -mask_import, the input dataset must match
the final grid of the processed data. Since you used
3dresample to make it 2.5 mm^3, I must guess that the
bounding box is not correct, meaning you used -dxyz
instead of -master.

The safest way to apply 3dresample (both here and in
general) is to use -master, which will match the grid
of an existing dataset, rather than just altering the
voxel size of the input dataset.

Try running something like:

3dresample -master full_mask+tlrc ...

to match the grid of the standard space data from
some subject. That mask should be appropriate to
import as you are trying.

Please let us know how it goes.

Thanks,

- rick