This error message can be tripped through one of two actions:
In File Options, "Prohibit modification of value..." has been selected on the Auto-Enter tab for the field that your action is trying to modify.
The field you are attempting to modify is of type calculation.
File and account permission settings will not produce this precise error message.
The field is a type of calculation. I've gone into the template, studied it - even changed names of fields to get a feel of how the script works.
The source field is a container (photo), which, when clicked gets dropped into a larger "display container - which is a calculated field.
It's all driven from a button assigned to the source container field. "when clicked, make picture bigger".
While I can drop my photo in the source container, when I click on it and it triggers the scripts, no dice. I get the message.
Is it possible that I have some fields missing that are in the template that I should have? I can't see what steps I've missed.
To modify the data shown in a calculation field, you cannot use this script step:
Set Field [YourTable::calculationfield ; Some expression goes here]
You'll get an error every time.
To modify what is shown in the calculation field, you have to modify one of the fields referenced in the calculation. Using simple number fields as an example.
If your calculation field, Field C, is defined as:
Field A + Field B
Set FIeld [YourTable::Field C ; 6 ]
will not work.
But you can use either
Set field [YourTable::Field A ; 3 ]
Set FIeld [YourTable::Field B ; 2 ]
(Or Both) to change the results shown in the field.