The error occurs when I did NotesDatabase.FTSearch(query, 0)
GTR search error for "D:\Domino\data\mydatabase.ft\ftgi": Work area overflown due to many hits. Error-Number = 299: Full text error; see log for more information
I've found that this problem happens because of this part of query: [AgrAddonNum]=("-" | "/")
query = (([Form]="AgrAddon") & ( ([AgrDate]=08.07.2005 & [AgrAddonDate]=25.06.2008 & !([AgrAddonNum]=("-" | "/")) )))
Actually for some reason (I did not figure why) symbols - , ; : \ are the reasons of error in FTSearch. So I changed query a bit to avoid such situation and it worked well after all.