Encoder init return error when using d3d11 memory and extbrc

Hello,

  I'm running encoder sample with "extbrc:on" and "d3d11" options, and MFXVideoENCODE_Init return MFX_ERR_UNKNOWN. But when i'm using system memory with extbrc, and it works fine.

  Could somebody tell me why and how to fix it?

Thanks!