Since you are using @searchga as the search function for sdo.optimize, perhaps you could try to pass in additional information along with the search function, similar to the way it is done in the "Search Options" section of this link:
that is, for the "SearchFcn" property, try to specify {@searchga, iterationLimit, gaOptions}, and you could create gaOptions using the "optimoptions" function, similar to how it is done in the following link:
