Ch cell type

My grid has some of its columns type as ch. The grid loads fine but iam not able to check or uncheck checkboxes. What could be possible reasons???

Please check is onCheckbox or onEditCell events used , both of events are blocable , and custom code attached to them must end with
    return true;
in other case event will be blocked, and edit operation ( changing checkbox state ) prevented.

Also edit operation for grid can be blocked by