When you want to post a key to a 4D View area, you must make the 4D View area the active object. You can do this by posting as many TAB key strokes as needed to make the 4D View area active. Take for example the following Code.

POST KEY(Tab )
PV GOTO CELL (area;1;1)
POST KEY(Ascii("S"))
POST KEY(Ascii("A"))
POST KEY(Ascii("M"))
POST KEY(Ascii("P"))
POST KEY(Ascii("L"))
POST KEY(Ascii("E"))
POST KEY(Space )
POST KEY(Ascii("T"))
POST KEY(Ascii("E"))
POST KEY(Ascii("X"))
POST KEY(Ascii("T"))

In the form, the 4D View area is the next active object. This is why you only see one TAB.