[FieldTrip] source statistics with ROI yields NaN clusters

[Vitória Magalhães Piai]

Dear all,

I'm trying to run ft_sourcestatistics with a specified ROI. It's data 
(MNEs) averaged over time.

If I run ft_sourcestatistics without an ROI, I get a cluster with prob = 
.178. It looks like this (figure attached), where I masked using the 
t-values.
Since I'm dealing with an N400-like component, I've got good reasons to 
expect the effect to be localised (mainly) to left temporal areas.

So I tried adding this to my cfg:

cfgst.atlas        =  'aal\ROI_MNI_V4.nii';
cfgst.roi          = {'Temporal_Mid_L'  'Temporal_Sup_L' 'Temporal_Inf_L' };
cfgst.avgoverroi   = 'yes';
cfgst.hemisphere   = 'left';
cfgst.inputcoord   = 'mni' ;
stat = ft_sourcestatistics(cfgst, iRel{:}, iIde{:});

If cfgst.avgoverroi   == 'yes'; I get the following error:

??? In an assignment  A(:) = B, the number of elements in A and B
must be the same.
Error in ==> clusterstat at 187
     tmp(cfg.inside) = postailobs;
Error in ==> ft_statistics_montecarlo at 326
   [stat, cfg] = clusterstat(cfg, statrand, statobs,'issource',issource);
Error in ==> statistics_wrapper at 298
     [stat, cfg] = statmethod(cfg, dat, design, 'issource',issource);
Error in ==> ft_sourcestatistics at 107
     [stat, cfg] = statistics_wrapper(cfg, varargin{:});

If cfgst.avgoverroi   == 'no';
ft outputs "found  positive clusters in observed data" and 
stat.posclusters/negclusters is only NaN. This is regardless of whether 
cfgst.roi is one label or a cell array.

Does anyone know what I'm doing wrong?
I've been completely stuck on source statistics for these MNEs for days, 
so /any/ help would be highly appreciated, even if it is to suggest 
another way to do the stats!

Thanks a lot, Vitória
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