Trouble in converting C code to D

[Suliman via Digitalmars-d-learn]

Jacob, thanks!

   double [6] adfGeoTransform;

   if( GDALGetGeoTransform( hDataset, adfGeoTransform.ptr ) == 0 )
   {
     writeln(adfGeoTransform[1]);
   }

But could you explain why if binding have next string:

enum CPLErr
{
     CE_None = 0,
     CE_Debug = 1,
     CE_Warning = 2,
     CE_Failure = 3,
     CE_Fatal = 4
}

I can't use:
if( GDALGetGeoTransform( hDataset, adfGeoTransform.ptr ) == 
CE_None )

>Error: undefined identifier CE_None