What's wrong with this SQL?

SELECT BA_Clients.SourceMedi,;
   Sum(IIF(BA_Clients.RespCode == "00", 1, 0)) AS Code0,;
   Sum(IIF(BA_Clients.RespCode == "01", 1, 0)) AS Code1,;
   Sum(IIF(BA_Clients.RespCode == "02", 1, 0)) AS Code2,;
   Sum(IIF(BA_Clients.RespCode == "03", 1, 0)) AS Code3,;
   Sum(IIF(BA_Clients.RespCode == "04", 1, 0)) AS Code4,;
   Sum(IIF(BA_Clients.RespCode == "05", 1, 0)) AS Code5,;
   Sum(IIF(BA_Clients.RespCode == "06", 1, 0)) AS Code6,;
   Sum(IIF(BA_Clients.RespCode == "07", 1, 0)) AS Code7,;
   Sum(IIF(BA_Clients.RespCode == "08", 1, 0)) AS Code8,;
   Sum(IIF(BA_Clients.RespCode == "09", 1, 0)) AS Code9,;
   Sum(IIF(BA_Clients.RespCode == "10", 1, 0)) AS Code10,;
   Sum(IIF(BA_Clients.RespCode == "11", 1, 0)) AS Code11,;
   Sum(IIF(BA_Clients.RespCode == "12", 1, 0)) AS Code12,;
   Sum(IIF(BA_Clients.RespCode == "13", 1, 0)) AS Code13,;
   Sum(IIF(BA_Clients.RespCode == "14", 1, 0)) AS Code14,;
   Sum(IIF(BA_Clients.RespCode == "17", 1, 0)) AS Code17,;
   Sum(IIF(BA_Clients.RespCode == "18", 1, 0)) AS Code18;
   FROM BA_Clients;
   GROUP BY BA_Clients.SourceMedi

It work fine form every SourceMedi non blank, but for SourceMedi blank, it return only Code11 = 1. There's 60 records (with RespCode between "00" and "18") with SourceMedi blank.

TIA