I've connected Authoize.net to my NationBuilder account. Donations are failing and I'm getting the error
"The Global Payment System identification numbers are incorrect. Call Merchant Service Provider."
This is not an error message generated by NationBuilder. It's coming from the payment processor side relating to a configuration issue.
According to Authorize.net, the error code first recommends checking in with the merchant services provider, which is the institution where you acquired your merchant account from.
After confirming, you'll next what to check with Authorize.net to make sure the information from the merchant services provider is configured properly in Authorize.net.
Complete and current information on how to use NationBuilder is available in the documentation section.