Separate Pricing Per Customer 4.2.2

[pasantos]

I install the contribution Separate Pricing Per Customer 4.2.2, and it is great.

Only gives a error in the backoffice in Orders:

 

1052 - Column 'customers_group_id' in from clause is ambiguous

select count(*) as total from orders o left join orders_total ot on (o.orders_id = ot.orders_id) left join customers c on c.customers_id = o.customers_id left join customers_groups cg using(customers_group_id), orders_status s where o.orders_status = s.orders_status_id and s.language_id = '1' and ot.class = 'ot_total'

 

Please it helps me,

What do make to solve the error?

 

Thanks