"A valid amount is required" error with Authorize.net AIM

[AvaAdorn]

I had deactivated Authorize.net for a few months when business was slow and I just reactivated and now I'm getting this same error: A valid amount is required. - Your credit card could not be authorized for this reason. Please correct the information and try again or contact us for further assistance.

It's sending a $0 amount but in USD. It was working just fine a few months ago and I didn't change a thing. I just disabled the payment module in my shopping cart and now I've enabled it but I'm getting that strange error. Where should I look to fix this?

[AvaAdorn]

Looks like it had something to do with applying store credit if it was available. If a value of $0 store credit is chosen, then it doesn't work. I guess it's a bug I need to fix.