[igraph] Problems with deleting vertices

[Julian Hagenauer]

Hello,
somehow igraph does not delete vertices for me. 
Am i doing something wrong?

> g<-graph.ring(10)
> vcount(g)
[1] 10
> delete.vertices(g,c(2,7,8))
IGRAPH U--- 7 5 -- Ring graph
+ attr: name (g/c), mutual (g/x), circular (g/x)
> vcount(g)
[1] 10

Thank you very much,
Julian