Multiple datasets Reporting Services problem

Hi All,
I have report that uses two datasets(both get image from database using the same stored procedure). Stored procedure needs one parameter ResourceKey. I defined new report parameter and specified default value for it. Now I have two report parameters(ResourceKey and ResourceKey2), one for first dataset and one for second dataset, with different names.
Then I assigned to second dataset parameter(ResourceKey2) I have defined earlier and first dataset has parameter ResourceKey.
Problem is that report shows me always two same images, instead of two different images. It looks like both datasets uses only ResourceKey.
Can someone help me, please?
Thank you.