Values missmatch in MIGO

Dear Experts,

   values are missmatching while doing PO. In PO the gross price is 950.50 USD for a material exchange rate has been maintained 1 USD = 53.5 INR while creating PO. while doin MIGO after a month d exchange rate is 1USD = 55 INR

so in MIGO for 2 materials values should be 950.50*2*55 =  104555

if it taking the old exchange rate then the value must be  950.50*2*53.5 = 101703.5

but in MIGO the value is different(not as per both exchange rate.  the problem is in MM part or FI part.

what exactly must be the problem ?

please advice me

Regards,

Gowrishankar R