GPG Subkey decryption

[John Ramsden]

I think I may be misunderstanding how I'm supposed to be decrypting with
a subkey. From what I thought, the public key should be the same on a
subkey as it is on a primary key. I see the same public key when I list
them on my machine which stores the primary key and the machine that
stores the subkey.

I want to send a message to the public key and be able to decrypt it on
any machine where I have any subkey of the primary key. I'm encrypting
from my primary key and using my public key from the same key as the
recipient. Do I have to define multiple recipients based on all the
subkeys? If so where do I find the public key for these subkeys that are
supposed to be the recipient?

When I'm on the machine that holds the sub key and I attempt to decrypt
I get the message:

> gpg: decryption failed: No secret key

-- 
  John