What happened to my Vanda lilacina buds
 

Four days ago my Vanda lilacina had three healthy looking stems with buds (first attachement). There was some tiny ants drinking liquid from the buds, so I did a search on the forum and apparently they was there drinking some sugar liquid from the buds. As fas as I could read, they should not be a problem to the buds or flowers.

But two days ago the buds started to turn white and the stems yellow and brown and look they have been sucked dry.

Today the stems and buds looks like attachement 2, 3 and 4.

Any idea what happened and how I avoid the same thing next year?