Oh, thanks for the output. I did not notice, but your commands include -regress_reml_exec and -regress_3dD_stop, so 3dDeconvolve is not being used to perform the regression. And unfortunately, 3dREMLfit is not able to create iresp output, that only works in 3dDeconvolve which is not being used.
You *can* use 3dbucket or 3dTcat to extract the betas of interest from the 3dREMLfit output. It is slightly inconvenient, but easy to do.
- rick