Strange Error Using Impex importing script
 

Hi,
this is my first post
I am running a phpbb3.0.0 forums[stable release]
i planned to convert it to vbulletin 3.6.8
i gathered some info from the internet that to import all my forums data from phpbb to vbulletin i need a script called "impex"
So, i downloaded the impex importing system ver:1.8
i have phpbb3.0.0 installed in /root/community/
for testing purposes, i installed vbulletin on a different host in
/root/vbulletin/
i installed impex importing system in
/root/vbulletin/impex/
i configured the "impexconfig.php" file and tried to import
i successfully imported all my users
i successfully imported all my forums
but,
when it comes to threads
i have got the following error:
....skipping....failed on forumid
and when it comes to posts, i have got the following error:
......skipping......failed on threadid

Now, i am totally trapped
Can someone please guide me where i am doing wrong!
Any help will be really appriciated
Thanks in advance :)