[igraph] Help interpreting warning message from dyad.census()

[capitano . nemo]

I have this graph

  simp_graph
  IGRAPH DN-- 84203 284955 --
  + attr: name (v/c), timestamp (v/c)

which when I

  dyad.census(simp_graph)

gives


  $mut
  [1] 24130

  $asym
  [1] 236695

  $null
  [1] 0

  Warning message:
  In dyad.census(simp_directreply_graph) :
   At motifs.c:899 :Integer overflow, returning zero

I am not sure what is generating the warning message. But I also have a 
problem with the statistics: considering my graph has 84,203 vertices 
the number of possible pairs is 3,545,030,503 or (84203*(84203-1))/2, 
then the results can’t be correct because 24130 + 236695 + 0 is only 
260,825.

Am I missing something?

Thanks

Francesco