I have a table of Schools. Each school has a category the ID of which is held as an integer in the field categoryID. There is another table, Categories, which holds 2 fields; categoryid and category. The categories have an ID of 1 to 5 with suitable text plus 99 for 'Not Known'. Except for the 'Not Known' category each category ID is the same as the record number in the table. There are no relationships defined between the tables in the data environment or the dbc. I have a form to display the details for each school with a combo box to show the category and allow the user to change it. If a school has a category where the ID is 1 to 5 then the category is displayed OK but if the category ID is 99, which is record 6 in the category table, then the category is not displayed. If I change the category ID in the Schools table from 99 to 6 then it displays 'Not Known'.

Combo box settings:
Style = 2 (Dropdown List)
RowSourceType = 6 (Fields)
Rowsource = Categories.Category, CategoryID
Value is empty
BoundColumn = 2
ColumnCount = 2
ControlSource = Schools.CategoryID

The combobox is obviously displaying the record based on the record number and not the ID. How can I make it react to the ID?