Granger Causality on Visual ERP

Good afternoon!!
I was trying to compute Bivariate NxN Granger causality on P100 VEP, I imported into database 378 epochs (215 good), I set the window time (in Granger causality menu) 98 - 121 (in order to catch de th P100 potential), order model 7, remove evocked potential, save as average connectivity matrix, and then, it crashed;


** Error: [process_granger1n] Connectivity > Bivariate Granger causality NxN
** Line 304: betainc
** W must be real and non-negative.
**
** Call stack:
** >bst_granger.m at 304
** >bst_connectivity.m at 354
** >process_granger1n.m>Run at 91
** >process_granger1n.m at 24
** >bst_process.m>Run at 229
** >bst_process.m at 36
** >panel_process1.m>RunProcess at 151
** >panel_process1.m at 26
** >gui_brainstorm.m>CreateWindow/ProcessRun_Callback at 772
** >bst_call.m at 28
** >gui_brainstorm.m>@(h,ev)bst_call(@ProcessRun_Callback) at 296
**

It is weird cause I was actually able to compute averaged erp and dipole without problems

Thanks in advance!

You input time window (20ms) is too small for estimating Granger causality.
I recommend you read about this technique before trying to compute in Brainstorm.

ok
you were right!
I increased the analysis time window and it worked!