FIX market data API -- INVALID_PERMISSION response upon Logon

upon sending a FIX LOGON message to the coinbase sandbox market data fix server (tcp+ssl:// I get an immediate LOGOUT message back with text (field 58) value ‘INVALID_PERMISSION’. I have tried generating a new API key with all permissions enabled but the result is the same. what does this response mean?
In my LOGON message I have as sendercompid (field 56) the client api key id
and as password (field 554) the api key password.