Structural Modeling in Quartus

I have tried structural modeling examples from Bhasker in Quartus . I cannot rectify the following error.

entity HALF_ADDER is

port(A,B: in BIT ; SUM ,CARRY:out BIT);

end HALF_ADDER;

architecture HA_STRUCTURE of HALF_ADDER is

component XOR2

port (X,Y:in BIT; Z:out BIT);

end component ;

component AND2

port (X,Y:in BIT; Z:out BIT);

end component;

begin

X1:XOR2 port map(A,B,SUM);

A1:AND2 port map(A,B,CARRY);

end HA_STRUCTURE;

ERROR

Error: Port "X" does not exist in primitive "AND2" of instance "A1"

Error: Port "Y" does not exist in primitive "AND2" of instance "A1"

Error: Port "Z" does not exist in primitive "AND2" of instance "A1"

Error: Can't elaborate top-level user hierarchy

Error: Quartus II Analysis & Synthesis was unsuccessful. 4 errors, 0 warnings

Error: Peak virtual memory: 216 megabytes

Error: Processing ended: Mon Dec 20 06:08:46 2010

Error: Elapsed time: 00:00:01

Error: Total CPU time (on all processors): 00:00:01

Error: Quartus II Full Compilation was unsuccessful. 6 errors, 0 warnings

Kindly also mention the right documentation to refer