improper error code when instantiating WePay

[MerryPlace]

WePay::useStaging($client_id, $client_secret);

$wepay = new WePay($access_token);

When I supply my app access token from my dashboard I get the error:

You are trying to use an access_token from production on stage

This error would make you think that I must be using my production app token (which I'm not), so why don't I try WePay::useProduction to match the token.
Nope! now I get the error:

You are trying to use an access_token from stage on production

Since I haven't changed the access_token, these two error codes are paradoxical.
I suspect it takes another type of access token but without a more useful error code, this is very very confusing.