Writeable did not match any valid parameter of the parser

In the GUIDE GUI.m file, I have a screen where I need to define a cell array variable that needs to be updated (add +1 to one of its elements) depending on which choice the user selects.

A code like this:

filename = 'participants.mat';
m = matfile(filename,'Writeable',isWriteable);
participantData = m.participantData;

Is giving me this error:

Error using matlab.io.MatFile (line 397)
Argument 'Writeable' did not match any valid parameter of the parser

I placed this in the OpeningFcn of the GUIDE GUI.

Input would be greatly appreciated.

[Muaaman]

Resolved: the problem here I believe was it is not suppose to be 'Writeable' but rather 'Writable', and it should say 'true' instead of 'isWriteable'.