[igraph] error.c:125: failed assertion `no<100'

[igraph . x . flushy]

Hi,
I'm currently building my own interface to igraph.
But after building some 100 Graphs it crashes with
error.c:125: failed assertion `no<100'

I probably forget to clean something but I have no idea what?
Functions for creating and destroying the graphs are included.
The only thing special is that I store for every node a name.

Or can I figure somehow out the size of the stack (or increase it).

Therefor I defined my own struct:
typedef struct {
  igraph_t * graph;
  igraph_trie_t * names;

} yap_igraph_t;

Construction code:
  yap_igraph_t * ygraph=malloc(sizeof(yap_igraph_t));
  ygraph->graph=malloc(sizeof(igraph_t));
  igraph_t * graph= ygraph->graph;
  //printf("%p \n ",ygraph);

  igraph_vector_t * v1 = malloc(sizeof(igraph_vector_t));
  igraph_vector_init(v1, 0);
  igraph_create(graph, v1, 0, IGRAPH_UNDIRECTED);
  igraph_vector_destroy(v1);

  ygraph->names=malloc(sizeof(igraph_trie_t));
  //I also do not  sure, why I need the next to lines both. But  
without it doesnt work
  igraph_trie_init(ygraph->names,0);
  IGRAPH_TRIE_INIT_FINALLY(ygraph->names,TRUE);

Destruction code:
  igraph_trie_destroy(ygraph->names);
  igraph_destroy(ygraph->graph);
  igraph_free(ygraph->names);
  igraph_free(ygraph->graph);
  free(ygraph);


Thanks in advance