Dear experts,
I'm trying to run NiiStat with lesion masks for VLSM analysis
I created the .mat files and the excel file is ready with the behavioral data. 
But when I try to run with the GUI i get a matlab error: 

Error using save
Unable to write file C:\Program Files\MATLAB\R2019b\NiiStat-master\NiiStatGUI\niistatGUI_cfg.mat: permission
denied.

Error in NiiStatGUI/GOButtonPushed (line 444)
save(fullfile(filepath,'niistatGUI_cfg.mat'),'GUIdata');
Error using matlab.ui.control.internal.controller.ComponentController/executeUserCallback (line 335)
Error while evaluating Button PrivateButtonPushedFcn.

I precise that I used Windows 10, Matlab R2019b, SPM12. 

Thank you for your help

Problem solved.