d3d11state: Handle structured buffers.
diff --git a/retrace/dxgistate.cpp b/retrace/dxgistate.cpp
index 2251688..83cdaad 100644
--- a/retrace/dxgistate.cpp
+++ b/retrace/dxgistate.cpp
@@ -291,6 +291,7 @@
 
     DXGI_FORMAT DstFormat = ChooseConversionFormat(SrcFormat, numChannels, channelType);
     if (DstFormat == DXGI_FORMAT_UNKNOWN) {
+        std::cerr << "warning: don't know how to convert format " << getDXGIFormatName(SrcFormat) << "\n";
         return NULL;
     }