figure-reference in text differs from figure number

[Wolfgang Engelmann]

Dear Lyx-Seelsorger

what did I do wrong: 
my list of figures shows correctly figure numbers numbered according to the 
chapters
e.g.
2.6
2.7
etc

however in the text it is referred to as

figure 2.3.1
figure 2.3.2

I am using book style
and the recommended [short caption]{long caption} legends
in order to avoid too long text in the LOF