call custom SQL function in ASP.NET

I made an SQL function in MSSQL2000. This is a function that get's a calculated heat emission. When I run the Query in MSSQL2000 the function works. It calculates every emission for every row. When I call this SQL function in VS2005, it says it does not recognize the function. Does anyone know what this may cause? thank you. For the people who are bored, I added the SQL statement. The error is at the function

SELECT TOP 15 tbProducts.prod_code, tbProductProperties.prop_height, tbProductProperties.prop_length, tbProductProperties.prop_type, tbProductProperties.prop_default_emission, tbProductProperties.prop_weight, tbProductProperties.prop_water_volume, tbProductProperties.prop_n_value, GetHeatEmission(50,70,20,[prop_default_emission],[prop_n_value]) AS customEmission FROM tbProductClassification INNER JOIN tbProducts ON tbProductClassification.clprod_fk_prod_id = tbProducts.prod_id INNER JOIN tbProductProperties ON tbProducts.prod_id = tbProductProperties.prop_fk_prod_id WHERE (tbProductClassification.clprod_fk_class_id = 3327) AND (prop_height >= '030') AND (prop_height = '060') AND (prop_lengthYou may try to use the full name of that function, like dbo.GetHeatEmission().