  Extended private information retrieval (EPIR) was defined by \cite{BCPT07} at
CANS'07 and generalized by \cite{BC09} at AFRICACRYPT'09. In the generalized
setting, EPIR allows a user to evaluate a function on a database block such
that the database can learn neither which function has been evaluated nor on
which block the function has been evaluated and the user learns no more
information on the database blocks except for the expected result. An EPIR
protocol for evaluating polynomials over a finite field $L$ was proposed by
Bringer and Chabanne in \cite{BC09}. We show that the protocol does not satisfy
the correctness requirement as they have claimed. In particular, we show that
it does not give the user the expected result with large probability if one of
the coefficients of the polynomial to be evaluated is primitive in $L$ and the
others belong to the prime subfield of $L$.
