With the introduction of Vouchers and your LeadCENTER wallet, we often get some confusion on how these relate to Real-Time Campaigns.
Vouchers can be used to pay for Real-Time Leads by selecting the voucher before launching the campaign however, if you do not have any cash in your LeadCENTER wallet, the campaign will not launch.
You will need to have at least the value of 1 lead in your LeadCENTER wallet before you are able to launch a new campaign. This is true because a voucher can be used on many lead types, real-time being only 1 of them, and in order to ensure you don't get leads that can't be paid for, you must have a balance in your account even if you intention is to pay with the allocated voucher.