You tried to execute the AsyncRead method with the same PropertyName of an AsyncRead that is currently in progress. This error has the following cause:
AsyncRead "file:c:\winnt\winnt.bmp", vbAsyncTypePicture, "MyPicture"
AsyncRead "file:c:\winnt\winnt.bmp", vbAsyncTypePicture, "MyPicture"
You would get the error on the second AsyncRead method.