Hi,
Try changing "-ThreshBrik 0" to "-ThreshBrik 1"
The program is looking for some statistic in the header.
I have not tested this with Zscr stats...
I am pretty sure it won't work with Zscr as there is no degrees of freedom associated with it.
I can work on adding support for the z score and cleaning up the error message.
In the meantime, you could try running it 3dttest++ without the option you chose that makes it a z score rather than a t score.
I think those are the etac, clustsim, or toz options.
thanks, Justin