Steps to reproduce:
1. create two loan products one of which top up enabled.
2. Disburse loan(non-top-up) on 01 January 2016.
3. Make first repayment on schedule date(say, 01 February 2016)
4. Create another loan account(top-up enabled) and check 'Is Topup Loan' and select the previous account and set 'Disbursement on' date as 01 February 2016(Last transaction date of previous loan account).
>Not allowing to submit and throwing the error:
Loan topup should not be allowed for disbursement dates prior to the last transaction date of the previous loan account but it should allow on same date.