In regards to which logs, the nolio_action_all.log will normally have something related to this error. You might find something there if you search for "Executing command".
In regards to the error I think this can happen for one of two possible reasons:
1. the owner of the release automation agent process (Iinux or windows?) does not have access/permissions to websphere's wlst.sh file/folder; or
2. you're trying to the action without the username/password fields filled out which:
a. relies on the agent's process owner to have access to the soap.client.props file (which is commonly found in profiles/<profilename>/properties folder); and
b. the soap.client.props being configured correctly.
If you supply a username/password to the action does it work? If so then permissions to the wlst.sh is okay and it is likely a matter of permissions to access the soap.client.props file, and the soap.client.props file being setup properly (which you can test outside of RA). If I am not mistaken I think the action has a field for specifying a directory. If the soap.client.props file is being used (due to the absence of supplying username/password to the action) then the action, if i'm not mistaken checks for that soap.client.props file by taking the the bin folder supplied through the action and looking for it in the ../properties folder. So you'll probably need to make sure that the bin folder you specify is also the correct bin folder by verifying that <the folder you give in the action>/../properties/soap.client.props is available.
Regards,
Gregg