The Maketurn included with DOS Planets, and older versions of Winplan, can not transmit build cancellations to the Host.
If you're using DOS Planets, use a different Maketurn program. All Maketurn programs known to work are listed in the next entry. However, many of the third-party maketurns might not encode cargo transfers generated by DOS Planets correctly, causing PHost up to version 3.4i/4.0f to reject the turns.
If you're using Winplan, PHost implements a workaround.
