I'm running the mkdfa.pl script from the same folder I've already put sample.grammar and sample.voca files. My OS is Windows 7.  I got the following error :

-----------

$ mkdfa.pl sample
sample.grammar has 1 rules
sample.voca    has 2 categories and 10 words
---
Error:       Can't open grammar file "/tmp/g4132.grammar"
Error:       Can't open grammar file "/tmp/g4132.grammar"
Error:       Can't open grammar file "/tmp/g4132.grammar"
Error:       Can't open grammar file "/tmp/g4132.grammar"
Error:       Can't open grammar file "/tmp/g4132.grammar"
Error:       Can't open grammar file "/tmp/g4132.grammar"
---
no .dfa or .dict file generated

---------

Any ideas ??