Exchange Rate Variance between PO and Receiving

Hello Guys,

Need your assistance...

I have a Exchange Rate Variance between PO and Receiving scenario  which is confusing for me. Exchange rate Variance is consuming budget from the Project budget but not from the Project Encumbrance in GL. Below is the behavior of transactions. Functional Currency is AED.

GL Budget

Budget                 Encumbrance                    Actual                   Available

1,000                     0                                              0                              1,000

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Created Project Budget amount 1,000 

Budget                 Encumbrance                    Actual                   Available

1,000                     0                                              0                              1,000

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GL After Baseline Project Budget

Budget                 Encumbrance                    Actual                   Available

1,000                     1,000                                     0                              0

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Created PO in USD 100 with Exchange rate of 5

100*5 = AED 500

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After PO Project Budget

Budget                 Encumbrance                    Actual                   Available

1,000                     500                                         0                              500

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Received PO fully but with exchange rate 6