SourceFileName macro in custom file adapter don't work

Hi,

I have custom file adapter, everything works fine except %SourceFileName% macro on send port (Send port is standard file adapter from biztalk).

In my adapter I write this property:

message.Context.Write("ReceivedFileName", "http://schemas.microsoft.com/biztalk/2003/file-properties", (object)ReceivedFileNameAndPath);

Why macro don't work?

Thanks.