Sirius and jail

[Aslı Tümerkan]

No: HPFGUIDX 167530

katmandu:
> Sirius doesn't seem to hold a grudge against him, and Dumbledore says
> he trusts Sirius.
>
> If he knew, because of Pettigrew, that Sirius was innocent. Why
> didn't he use the above means to prove his innocence? After all,
> there were 4 other people who saw Pettigrew.


Asli:
First, I'm new to the group, and I'm sorry if I'm doing anything not
according to the rules.

In F.A.Q on JKR's site, somebody asks how the ministry couldn't
find Sirius Black by sending him an owl. The answer is:

"Just as wizards can make buildings unplottable, they can also make
themselves untraceable. Voldemort would have been found long ago if it had
been as simple as sending him an owl!"

However, if he made himself untraceable how can Hedwig find him? Did he make
himself untraceable for everyone but Harry? How is that possible? Did J.
Rowling make a careless mistake there?