Migrating / importing seamonkey mails to thunderbird with all data

I have been using seamonkey mail from 1 year as one of the friend suggested on eTI to use it. It is good but now I am facing problem with it. It crashes too frequently after recent update and now I want to switch to Mozilla thunderbird mail cleint. I have installed it and liked but the import feature is not working. I want to import my all seamonkey mail to thunderbird along with all data ? When I try to use import function of Thunderbird, from tools->import , on clicking finish, nothing happens ?

I am using seamonkey virsion 2.26.1 and my os is windows 7.

If anyone have experience with it then please tell me how can I migrate from seamonkey mail to mozilla thunderbird without loosing any data.