sbillard on "Issue loging in from Plugin"

you can use the DEBUG_LOGIN define to gather more data on your problem.

But some comments on the code snippet you have posted.

is "decode64" supposed to be base64_decode?

$_zp_authority should probably already be defined unless the plugin is loading "bare" in which case you won't have other needed functions, so I doubt that is true.

Otherwise the code looks right. If you get an empty result form the getAnAdmin it means that there was no database entry that matched your parameters.

I suggest you log the input parameters to be sure they are not being corrupted.