Power pivot - yellow error message saying 'relationship between tables may be needed'

Hello

This is the first time I use power pivot in excel and I am stuck and was wondering if anyone can help.

I have input two tables into power pivot and linked them. The link is shown on the relationship tab.

However when I insert a pivot table - the two tables show but I get the above error message which says 'relationship between tables may be needed'.

However, when I click on manage relationship - it shows the link between the two tables so I don't understand why the pivot table field list is not linking the two tables together.

Can anyone help?

Thank you

Kind Regards

Juniper

Sorry if my terminology is a bit off - im learning...