Currency Rate not populating in PO distribution from PO header

We have created a agreement in USD with currency rate as 59.Then created a requisition in INR. After approval of the requisition selected the agreement and req in Autocreate form. But currency rate is not populated in PO. Currency rate is of USER type. So manually changed the currency to USD from INR and entered Rate date and rate as 60. But after saving the rate is not populated to PO distributions and buyer has to manually enter the rate again at PO distribution.