Hi,
Why have you activate the option "address override" ?
We didn't implement the "bitpay" plugin so it is difficult for us to provide support on a plugin we don't have the knowledge.
What I can told you is that the bitpay call for the creation of the invoice, failed.
It could be a wrong apiKey for the bitpay.com platform.
You should have a log file in the plugin folder (named "bplog.txt"), it will contain more details about the problem.
Regards,
Jerome - Obsidev.com
HikaMarket & HikaSerial developer / HikaShop core dev team.
Also helping the HikaShop support team when having some time or couldn't sleep.
By the way, do not send me private message, use the "contact us" form instead.