DataSource Controls :: QueryString Parameter Not Working?

this has to be a simple thing but I am missing it

here's what i have

the null condition and query works

the not null condition does not

I have tried:

ImageID=@id error myust declare @id
ImageID=id invalid column id
ImageID=?id incorrect syntax at ?
all errors occur at SqlDataReader Dr = Cmd.ExecuteReader();
int id = Convert.ToInt32(Request.QueryString["id"]);
string SQLquery ="";
if (id == null)
{
SQLquery = "Select Top 1 ImageData,ImageType from WebBGImages ORDER BY NEWID()";
}
else
{
SQLquery = "Select ImageData,ImageType from WebBGImages where ImageID=@id";
}
SqlCommand Cmd = new SqlCommand(SQLquery, connection);
SqlDataReader Dr = Cmd.ExecuteReader();