This message just means that an attribute of your element has a value which isn’t allowed.
For example, the variable ‘priority’ might be defined as ‘High’, ‘Medium’ or ‘Low’. If this has been given a value of ‘Very High’, then this message will appear.
Just double-click the element in the diagram, and select al allowed value from the drop-down list.
How can this happen?
If you are using Model Expert, then you will usually use the ‘Custom User Interface’, which shows you which values are allowed for each type of attribute/field.
But you can also edit this data in EA directly, or values might be set by a script.