This message is returned by the Pick phantom process WEBSERVER. It is telling you that it did not know what Pick subroutine to call.
Are you sure this subroutine was compiled properly? Is it cataloged?
If you are using CGI not PHP, this could be caused by a missing attribute in the PROPERTIES file. See the SCRIPTS item. Each attribute in the SCRIPTS record represents 2 values that control routing a URL to a Pick BASIC subroutine. One value is for the web URL and one value is for the cataloged Basic program to run.
If using PHP you do not need to update the SCRIPTS item. It is not used. PHP can call D3 Subroutines directly by cataloged item-id.