fanpage import - error when working with past time intervals

Feb 1, 2013 at 8:13 PM

when downloading user by post networks and ask the importer to do so on the base of comments, i always get an error; whereas everything is fine if i only ask only for likes. the error i get is this:
"the network could not be obtained - [indexoutofrangeexception]"

to give you more details: i am trying to scrape back the same page i was working on last summer and i am working on past dates so i get this error when i aske for posts in the period 1 jan 2011 to 31 jan 2011. however if i change dates, i continue to have the problem (I have tried 1 feb 2011 - 28 feb 2011). however, if i ask for likes and comments on the last 2 posts i get them. so my guess it is that the problem arises when working with past data...

any insights?
thanks in advance