Exchange rate difference in MIGO and MIRO

Dear Experts,

Our local currency is INR.

We have created PO and MIGO on 31.03.2015 with exchange rate 62.5908 without tick on fixed exchange rate in PO. OB08  is  also same on 31.03.2015. But at the time of MIRO system showing error massage for configure KDM even if i put exchange rate manually (62.5908) in MIRO.

                    GR/IR  Dr         62.5908

                           To Vendor        NIL 

                    Total                  63.5908

I have also made down payment to this in UDS

Please advice how can i debug exchange rate 63.5908. if i assign GL on KDM then system will debit this difference in that GL

Thanks in advance. Your suggestions will be highly appreciated.

Best Regards,