Endpoint Encryption

My coworker created a bunch if PGP codes, when I go to unlock things from my computer certain PGP files will unlock, but other do not. There is this one PGP key that won't unlock for me. What can I do to solve this on my end.

Here is the error below. I right click on the file and then choose Symantec Desktop Decryption and then I click on decrypt & verify.

Symantic Encryption Desktop - Enter Passphrase

PGKey <Kate@dh.com> (DH/2048)

1 unknown keys (s)

ITis not possible to decrypt this message because your keyring does not contain usable private key (s) corresponding to any of the above publickey(s).

Hi Wsilage,

The file is encrypted to two keys, out of which the keys for Kate is available in you PGP desktop under PGP Keys section. The other key showing as unknown is not in your keyring.

You can access the files which are encrypted to your keys and it will show up in the list of keys that have access to the file.

Hi Wsilage,

Any update on this? 
Please do let us know if you need any further information on this issue.