You can not purchase virtul money with virtual money

Hello All,

I am using this plugin, it looks great.

But I am facing few issues while using it. When I have $20.00 in my wallet and purchasing a product worth $10.00. At checkout page I ma getting below mentioned error :

Payment error: You can not purchase virtul money with virtual money. Please choose another payment method.

Why I am getting this. Please help !

Thanks
Sunil

https://wordpress.org/plugins/user-waller-credit-system/