why accept my FB request and then not reply to message?

[me&lovedbabybump]

Im not that great with FB infact i have a love hate relationship with it because its soooo intrusive however ii live overseas and love to stay in touch with freinds and fam

but theres one thing that reallly irks me!!!!!!

There are times i requested people, people i have had genuine past connections with, even gone to school with and when i send the opening message with the request, i get accepted straight away, but i dont get a response from the personal message

this baffles me, i find it sooo rude, its like you open the door to your home and they dont want to speak with you but just come in, have a look around, your life, your photos and thats it ;;;for me this is invasive and rude, why accept in the first place

what do you guys think??? thanks in advance