Reload the protocol

I open the protocol in the brainstorm, but there is a issue about the reload the protocol as screenshot. I have tried to reload, but it doesn't work. How should I do?

Please verify that the file channel.mat exists in your HDD database.

The full path to that file can be obtained with the following commands:

protocolInfo = bst_get('ProtocolInfo');
bst_fullfile(protocolInfo.STUDIES, 'EPCTL012', 'SEEG', 'channel.mat')