Augustus made no effort to contact Postumus until AD 14.
In the summer of that year, Augustus left Rome, never to see the capital again.
The main ancient sources of information about this period, Tacitus and Cassius Dio, suggest that Augustus left Rome in the company of only one trusted friend, the senator Paullus Fabius Maximus.
The two left for Planasia to pay Augustus' banished grandson a highly controversial visit.

Fabius and then Augustus himself died on their return, without revealing what they had been doing.
Tacitus reports their visit to Planasia as a rumor, although Dio reports it as fact.
According to the historian Robin Lane Fox, the alleged visit has sometimes been dismissed by modern scholars.
However, it has been shown that Augustus and Fabius were absent from Rome in mid-May of AD 14.
At this date, Augustus' adopted grandson, Drusus the Younger, was being admitted into the Arval Brethren, and an inscription (ILS, 5026) shows that both Augustus and Fabius voted in absentia to admit him into the priesthood.

There was much gossip over the outcome of their expedition.
Tacitus recounts the rumor that Augustus had decided to reverse his decision and make Postumus his successor.
In his account, Fabius indiscreetly told his wife what had occurred during the trip, and it cost him his life.
Augustus' wife Livia, too, was said to have poisoned her husband in order to prevent Postumus becoming the successor and thus supplanting her son Tiberius.
While modern historians, including Fox, agree that such stories are highly unlikely, there is evidence that Augustus' journey was historical. "
It is the last act in Augustus' long marathon of finding and keeping an heir to the new Empire".
Augustus made no effort to contact Postumus until AD 14. In the summer of that year, Augustus left Rome, never to see the capital again. The main ancient sources of information about this period, Tacitus and Cassius Dio, suggest that Augustus left Rome in the company of only one trusted friend, the senator Paullus Fabius Maximus. The two left for Planasia to pay Augustus' banished grandson a highly controversial visit. 
Fabius and then Augustus himself died on their return, without revealing what they had been doing. Tacitus reports their visit to Planasia as a rumor, although Dio reports it as fact. According to the historian Robin Lane Fox, the alleged visit has sometimes been dismissed by modern scholars. However, it has been shown that Augustus and Fabius were absent from Rome in mid-May of AD 14. At this date, Augustus' adopted grandson, Drusus the Younger, was being admitted into the Arval Brethren, and an inscription (ILS, 5026) shows that both Augustus and Fabius voted in absentia to admit him into the priesthood.
There was much gossip over the outcome of their expedition. Tacitus recounts the rumor that Augustus had decided to reverse his decision and make Postumus his successor. In his account, Fabius indiscreetly told his wife what had occurred during the trip, and it cost him his life. Augustus' wife Livia, too, was said to have poisoned her husband in order to prevent Postumus becoming the successor and thus supplanting her son Tiberius. While modern historians, including Fox, agree that such stories are highly unlikely, there is evidence that Augustus' journey was historical. "It is the last act in Augustus' long marathon of finding and keeping an heir to the new Empire".
Agrippa Postumus