 Complete the following phrase:  International scheduled services proved difficult to successfully establish until the late 2000s, when a weekly seasonal service between Düsseldorf and Inverness commenced in summer 2009, operated by Lufthansa CityLine, and in 2011 when Flybe commenced daily operations to Amsterdam. The now-defunct Snowflake a low-cost subsidiary of SAS operated a twice-weekly service to Stockholm in the summer of 2004, however the service was withdrawn after a short period of operation, owing to lack of demand. KLM uk operated a daily service to Amsterdam via Edinburgh in 1997 but this was short-lived, lasting only a few months. ScotAirways launched a service to Amsterdam in 2001; however, this was withdrawn following the 