Fetchhing price from db to textbox

Question

i want fetch a single data named price from db to textbox but it yeilds 0

#My Stored procedure

 

GO

alter PROCEDURE [dbo].[spGetPrice]

@productId as int,

@categoryId as int,

@price as int output

AS

BEGIN

SELECT @price=price from product04 where product_id=@productId and category_id=@categoryId

END

GO

 

#My dll

conn.Open();

SqlCommand cmd = new SqlCommand("spGetPrice", conn);

cmd.CommandType = CommandType.StoredProcedure;

cmd.Parameters.AddWithValue("@productId", DbType.Int32).Value = productId;

cmd.Parameters.AddWithValue("@categoryId", DbType.Int32).Value = categoryId;

cmd.Parameters.Add("@price", SqlDbType.Int);

cmd.Parameters["@price"].Direction = ParameterDirection.Output;

price=Convert.ToInt32( cmd.ExecuteScalar());

#My bll 

int price;

try

{

price = dal.GetPrice(categoryId, productId);

return price;

}

catch

{

throw;

}

#code behind

protected void btnGetDetails_Click(object sender, EventArgs e)

{

int productId=Convert.ToInt32(txtProductid.Text);

int categoryId=Convert.ToInt32(txtCategoryId.Text);

txtPrice.Text = bll.GetProductPrice(categoryId, productId).ToString();

}