Hi,
When I try to register a group, on the "please check data below" page, I get the proper billing info, but for each registrant, I get the following (eg)
Group Information
Member 1
First Name = Array
Last Name = Array
Please download DT Register again and you'll find the package has been updated to 2.6.7d. After updating, you should find this issue resolved. If not, lot a support ticket please. Thanks.