Losing passwords of users while converting from MyBB 1.4 to vB 4.0.8

[Doublecrosser]

Hi guys,

So, I have been using MyBB on my site from beginning.

Now i am interested in vBulletin.

So, i installed vB 4.0.8 and converted the MyBB board to vBulletin using the ImpEx Import system.

But now, i found the problem that the members cant login with their password which they used in MyBB.

Why is this happening? and is there a way to fix this?

Note : The version of Impex Import system i used was 1.96