Problem with exchange rate

Hi ,

I have a problem with exchange rate , when i run a reoort i am getting the following error

No exchange rate from CAD to USD and date 00/00/0000 found (currency transl. Z_M_ENDB/ZAVG)

No exchange rate from EUR to USD and date 00/00/0000 found (currency transl. Z_M_ENDB/ZAVG)

No exchange rate from PLN to USD and date 00/00/0000 found (currency transl. Z_M_ENDB/ZAVG)

No exchange rate from SGD to USD and date 00/00/0000 found (currency transl. Z_M_ENDB/ZAVG)

Can any one say what could be the reason for this error .

Regards,

Prasad