Subject: Why is there an increase in boiling point from H sulphide to H selenide?

The above question is an extract from  the 1998 Irish leaving Cert exam.  The 
information given is as follows: 

Hydrogen combines with oxygen, sulphur and selenium to form water, 
hydrogen sulphide and hydrogen selenide respectively.  The boiling points 
of this three hydrides are 373 k for water, 212.3 k for hydrogen sulphide  
and 231.3 k for hydrogen selenide.  Explain both the large decrease in 
boiling point from water to hydrogen sulphide and the increase in boiling 
point from hydrogen sulphide to hydrogen selenide.

While I understand the first part of the question, I'm unsure as to why 
hydrogen selenide has a higher boiling point that hydrogen sulphide.  As I 
thought that the lower the ionisation energy the lower the boiling point.  
Has it got something to do with s, p, etc. configuration?

I would appreciate it if you could help me with this question.  Thanking 
you in advance.  
Michelle

Re: Why is there an increase in boiling point from H sulphide to H selenide?