"format error in lattice file"?

[Christopher Kermorvant]

Hi,

I'm trying to use lattices and language models. I have a lattice of
words coming from a low level decoding process (each word is
associated to a probability).

If I use 

lattice-tool.exe -in-lattice my_lattice.pfsg -viterbi-decode

I get the best path in this lattice. So far so good.

Now I want to add a language model to this decoding. But if I use 

lattice-tool.exe -in-lattice my_lattice.pfsg -viterbi-decode -lm
my_language_model.bo

it seems that I get the best path according to the language model, not
taking into account the low level probabilities.

Am I right ? Is there a way to decode with both probabilities ?

Thanks in advance,

--
C. Kermorvant