rsatoolbox-SPM error: mask preparation

Hey everyone,

I’m conducting the RSA analysis using rsatoolbox on multiple ROI RDMs. I’m trying to load multiple ROI masks into my analysis with

 for i = 1:numberofmasks
        userOptions.maskPath{i} = fullfile(masks,sprintf('%s.nii',userOptions.maskNames{i})) ,

and I’m getting very peculiar error in mask preparation phase:

Dot indexing is not supported for variables of this type.

Error in spm_check_orientations (line 24)
dims = cat(1,V.dim);
Error in spm_read_vols (line 25)
Error in rsa.fmri.fMRIMaskPreparation (line 94)
			maskMatrix = spm_read_vols(spm_vol(readPath));

When I remove the .nii extension the SPM spm_vol line 61 & 55 screams that mask file doesn’t exist.
Does anyone know what’s the issue here and how to fix it?