Diagnosis
You tried to invoke the graphics. To do this, you have to select thedata models and entity types to be included in the graphics and thenactivate the graphics pushbutton.

Procedure
Select the data models and entity types you wish to display using thegraphical editor. To do so, position the cursor on the selected nodeand activate one of the pushbuttons explained here:
Select/deselect node
This marks the selected node.
Sel./desel. sub-tree
This marks the selected node along with the dependent sub-tree.
If you wish to display a data model with all associated entity typesand data models using the graphics function, position the cursor on thedata model you require and activate the pushbtton "Select/desel.sub-tree" followed by the pushbutton "Graphics".