Eagle Schematic - adding net does not reflect changes in PCB
Are you sure the schematic and board are in sync?  Are you adding a net between pins on the schematic?

Beyond that, it is difficult to come up with a meaningful answer with such little information.

Added:

You now say you are not adding a net between pins on the schematic, and no, I really can't see much of anything from those screenshots.  Without actually connecting pins, Eagle doesn't know the connection exists.  As a result, it doesn't show any airwire for the connection in the board, since there is in fact no connection.

Go to the schematic and use the NET command to draw a connection between two pins you want connected.  That should cause a airwire to show up in the board.  Alternatively, you can draw a short stub using NET from each pin, then give both stubs the same name.  One way or another, you have to explain to Eagle that the two pins are connected.  Once you do that, the corresponding airwire will appear in the board.