A/R Invoice should be open while partial payment

I am having a problem in incoming payment.

1. Firstly i made one A/R Invoice of Rs. 10000.

2. Then in incoming payment by using payment means i had made the partial payment of Rs 4000.

According to logic A/R Invoice should remain Open, but its not happening the status of A/R Invoice is getting closed.

Please solve my problem how i make A/R Invoice Open in this situation.

Thanks-

Nitu