Ms Sql stored procedures with parameters

Hi, I've done it in various ways, still, no luck.. Lets say i have a stored procedure getSomeCoolData declared as : [getSomeCoolData] @prodCode char(255), @prodName nvarchar(255), @prodID int = NULL This stored procedure returns products based on parameters i pass. So let's say i do like this in Enterprise manager: EXEC getSomeCoolData @ prodName = NULL, @prodCode = '061451221' And i get one product - good ! (by unique code) Now, let's say i'll do the same in php: $result = mssql_query("EXEC getSomeCoolData @ prodName = NULL, @prodCode = '061451221'"); BAM ! I get all the products, as all parameters where supplied as NULL or '' ( stored procedure checks for parameters, and if they are '' , it asigns null. Have tried various ways, still the same. Have tried to use http://www.sitepoint.com/article/php-microsoft-sql-server/2 - the same Any ideas?