foreign exchange rate

Hi gurus,

i have entered the exchange rate using t_code OB08. our local currency is NAD so i entered direct quot 1NAD = 7 USD. but when i capture an invoice in USD i am not getting the right amount in local currency. the system is using a different rate which i don't know where it is getting it from. is there some settings that i m missing or what could be the problem? this also happens for purchase orders.

please advice. points will be awarded.