This error occurs when the names of your data markers do not match the fields of the ADO recordset you are using as your data source.
For example, if your workbook has these data markers:
%%=categoryID
%%=description
Then the ADO recordset you assign as a data source must contain fields named "categoryID" and "description".
In order to be sure your ADO recordset has properly named fields, it is a good practice to use those field names explicitly in your SQL query like this:
SELECT categoryID, description FROM categories
If you use a generic select, as in:
SELECT * FROM categories
The query will still work if the database has the correct column names. However, it will be significantly less efficient as extra columns will be copied and subsequently ignored.