Hi Vincent,

If your AFNI version isn't too old, the 3dDeconvolve output should
come with details on the error. In any case, you might consider
this thread, found by a "misfit error" search:

[afni.nimh.nih.gov]
[afni.nimh.nih.gov]

Here is the 3dDeconvolve output, if you don't have it:

*+ WARNING: ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
*+ WARNING: stats.+tlrc[9] scale to shorts mean misfit error = 5.2% -- * Caution
+ a) Numerical precision has been lost when truncating results
from 32-bit floating point to 16-bit integers (shorts).
+ b) Consider writing datasets out in float format.
In most AFNI programs, use the '-float' option.
+ c) This warning is a new message, but is an old issue
that arises when storing results in an integer format.
+ d) Don't panic! These messages likely originate in peripheral
or unimportant voxels. They mean that you must examine your output.
"Assess the situation and keep a calm head about you,
because it doesn't do anybody any good to panic."
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

- rick