Creating Graph View Issue

At Point of Sale Orders, I wanted to add a Graph View where it can be grouped by (Shop) I've successfully added the field 'shop_id' to the tree view, then to the group by at search view. through inherited views for each. I've created a graph view for the object: pos.order Architecture: Later I've added a graph view in the action, so the graph view button appears right after the list view (tree) problem is ... The graph appears without proper data. Par type shows 0 sales, though there are posted orders Pie type shows NaN% regardless of trying to group by other fields. I noticed that this problem also happens at the account.account model graph view Could you please help me with this case ?