If you have created an API key and it is not pulling any information or if its access is not sufficient, then it's likely that you have not selected any information that the key is allowed to access.
This lack of access is reflected in your keys 'Access Mask'. If the 'Access Mask' is displayed as '0' then your key is not able to access any information about your character or account.
To grant access to information you can click on the relevant section such as WalletTransactions', 'CharacterInfo', 'SkillInTraining' etc. The section should turn orange and the 'Access Mask' number will update.
Once you select the various sections and then click on the 'Submit' button the key should be able to pull information about your account or character.