The Invalid Entity is issued in the following situations:
<entity> must have at least one attribute: You have an entity with no attributes.
You must add attributes to this entity. How?
<entity> identifier attribute data type must be set to 'Integer' or 'Text': You have an entity whose identifier is not of type Integer nor Text.
Select the Identifier attribute and change its data type to Integer or Text.
<entity> identifier attribute must be set to 'Mandatory': You have an entity whose identifier is not mandatory.
Select the Identifier attribute and change it to be mandatory.
<entity> can only have one 'Auto Number' attribute: You have an entity with more than one sequential attribute and this situation is not allowed; you can have only one sequential attribute per entity.
Check your entity and choose which attribute must be sequential. In the other attribute, you have to un-check the Auto Number property. How?
<entity> must have a table name: You have an entity with no physical table name.
Edit this entity and specify the Table Name property. How?
<entity> already uses table name <table>: You have more than one entity using the same physical table name.
Edit one of these entities and change the Table Name property. How?
Add an Entity | Entity Attributes | Error Messages