Lock box postings.. second posting is not happening.

Hi,

I configured lock box settings in dummy environment and when the lcok box file is processed the postings are

1. Bank Claring Acct Dr

Customer Cr (clearing of cusotmer open item)

2. Bank GL acct Dr

Bank clearing Acct Cr

But when lock box file is processed for customer (real time data i mean) only one posting is happening..

1. Bank Claring Acct Dr

Customer Cr (clearing of cusotmer open item)

I am not able to understand why the second is posting is missing? could any one of you help me with this?

Thanks,

Sree