Error:cannot convert 'Command.CommandType' to'System.Data.CommandType'

[doanminhchau]

Command cmd = e.Command;
              switch (cmd.CommandType)
              {
                  case CommandType.Login:
                      {
                          string name = SetManagerName(cmd.SenderIP, cmd.MetaData);
                          if (!IsNameExists(cmd.SenderIP, name))
                          {
                              SendUserOnlineList();
                          }
                          else
                          { 
                              Command sendcmd = new Command(CommandType.NameExists, cmd.SenderIP);
                              sendcmd.SenderIP = serverIp;
                              sendcmd.SenderName = "server";
                              client.SendCommand(sendcmd);
                          }
                          break;
                      }

I'm writing this code, but I got the error: Error 2 Argument 1: cannot convert from 'Command.CommandType' to 'System.Data.CommandType' D:\Laptrinh\topup\System Programming\Nha\UITChatServer\Server\ClientManager.cs 120 47 Server
Please give me any advice about this error? Thanks for any help.