why Ganesh sir has always His door closed while Rama mam

This is a very interesting question which has been hammering my mind from the fourth day after I entered in to EMU as SRF.In the initial days as I had a lot of works to do i.e. y I did not get any time to think upon these type of trivial issue(!!!!!!But later I realized that this is not a trivial issue.A Phd can be done to find the reasons behind it).Initial part was simple also and it required my engineering mathematics knowledge.Any way I am writing about door not the project here.So many people might be aware of this concept.But those who are not aware of this believe me this is true you can easily varify it with no initial setup( but only in week days(Mon-Fri)).I have spent more than a month here and I'll stay here for next two weeks only.And I'll reach there @ Varanasi with one unresolved question
Why Ganesh sir has always his door closed while Rama mam ????