Cannot add books into iBook anymore ?

ipod touch gen4 - ios 5.0.1:
didn't use itune because requires me replace exist books, used ifunbox, itools sync epub/pdf until can't add more books.

tried update new version of ibook yesterday when ipad 3 came out. problem same.

don't know if programs have problems or ipod does.

has any1 got same trouble? please show me how fix.

thank reading , reply!​

 

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