Passing DataField value as Input Parameter in SSRS

Hi,

I need to pass Dataset1 Field value(ex: CountryName) as input report parameter for Dataset2 in SSRS. I have assigning its Parameters properties called Default values and available values. But it always show the records from dataset2 based on first country Field value only. its not a country specific records.

Actually i need to pass specific CountryId as parameter to get the related records from dataset2. There are list of country values(like Aus,US) available in dataset1. I need to get records from dataset2 with respect to specific countryid.

Thanks in Advance.