Example error message
You cannot edit this field in the Power Player edition.
In the Power Player edition (or the edition you are using as it appears in the message), you can browse models, change inputs and recomputed results, but you are not allowed to change the internals of the model, including values or table cells for non-input variables. When you see this message, you've attempted to make such a change.
The person who build the model may not have intended you, as a user of the model, to have the ability to change this field. You should consult with the model author to see if this is the case. If this field is within an edit table of definition, then the author could modify the model to allow it to be edited by making an input node for that variable.