decrypt and secret key location

[Bruno Costacurta]

Hello,
I received an encrypted file called 'test.asc' (recipient is correct, 
hereafter it is truncated) but trying to decrypt it I 
have following error :

gpg --decrypt test.asc
gpg: encrypted with 2048-bit ELG-E key, ID 0CC897B5, created 2006-06-11
      "Bruno Costacurta <bruno at __nospam_here__org>"
gpg: decryption failed: secret key not available

Is it only key location?
If so, how / where can I indicate my private key location ?
If not, what type of problem ?

Many thanks for help,
Bruno Costacurta

-- 
PGP key ID: 0x2e604d51
Key : http://www.costacurta.org/keys/bruno_costacurta_pgp_key.html
Key fingerprint = 713F 7956 9441 7DEF 58ED  1951 7E07 569B 2E60 4D51
--
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