How to specify versions of ports?

[Max Brown]

Hello,

this is probably a silly question, but...

How do you specify versions of ports to be installed?

I tried upgrading ghc from 6.6_2 to 6.6_3 but the compile fails. I now
want to have my old version back, of which I still have a package.

I am in
/opt/local/var/db/dports/packages/darwin/powerpc

I can see that I have several packages of ghc, including the one that
I want 6.6_2
$ ls ghc*
ghc-6.6_0+darwin_8_powerpc.powerpc.tgz ghc-6.6_2+darwin_8_powerpc.powerpc.tgz
ghc-6.6_1+darwin_8_powerpc.powerpc.tgz

I want to install it:
$ sudo port install -b ghc @6.6_2
Error: Target com.apple.unarchive returned: Archive for ghc
6.6_3+darwin_8_powerpc not found, required when binary-only is set!
Error: Status 1 encountered during processing.

Why does this not work? What do I need to do?

Thanks,

Max