The panel needs one more constraint to finalize its position. In this next selection set, you select the XZ plane of the assembly and the XZ plane of the panel.
In the browser, select the XZ Plane, nested under the assembly origin folder. The plane highlights in the graphics window (click the following image to watch an animation of this selection).
In the browser, select the XZ Plane, nested under the origin folder for the panel part (click the following image to watch an animation of this selection).
Note: Since work features, such as workplanes, are abstract geometry and you are not selecting a specific face, you can select them in the browser.
Note the direction vectors on each plane. If the direction vectors are pointing in the same direction, you can place a Flush constraint. However, in this case, the direction vectors are pointing towards each other so you must change the solution type to Mate before you apply the constraint.
Select Mate in the Solution field of the Place Constraint dialog box.
Click the following illustration to see how the constraint previews.
Click OK to create the constraint and close the dialog box. The panel is now fully positioned.