SQL & PL/SQL

Hello I am using version 11gR2 using the UTL_FILE function to read from a text file then write the lines where it begins with word 'foo' and end my writing to the text file where the line with the word 'ZEN' is found. Now, I have several lines that begin with 'foo' and 'ZEN' Which make for one full paragraph, and in this paragraph there's a line that begins with 'DE4.2'. Therefore,
I need to write all paragraphs that include the line 'DE4.2' in their beginning and ending lines 'foo' and 'ZEN'

FOR EXAMPLE:

FOO/234E53LLID
THIS IS MY SECOND LINE
THIS IS MY THIRD LINE
DE4.2 THIS IS MY FOURTH LINE
THIS IS MY FIFTH LINE
ZEN/DING3434343

FOO/234E53LLID
THIS IS MY SECOND LINE
THIS IS MY THIRD LINE
THIS IS MY FIFTH LINE
ZEN/DING3434343

I am only interested in writing the first paragraph tha includes line DE4.2 in one of ther lines Not the Second paragraph that does not include the 'DE4.2'

Here's my code thus far:

CREATE OR REPLACE PROCEDURE my_app2 IS
infile utl_file.file_type;
outfile utl_file.file_type;
buffer VARCHAR2(30000);
b_paragraph_started BOOLEAN := FALSE; -- flag to indicate that required paragraph is started

BEGIN
-- open a file to read
infile := utl_file.fopen('TEST_DIR', 'mytst.txt', 'r');
-- open a file to write
outfile := utl_file.fopen('TEST_DIR', 'out.txt', 'w');

-- check file is opened
IF utl_file.is_open(infile)
THEN
-- loop lines in the file
LOOP
BEGIN
utl_file.get_line(infile, buffer);
--BEGINPOINT APPLICATION
IF buffer LIKE 'foo%' THEN
b_paragraph_started := TRUE;
END IF;
--LOOK FOR GRADS APPS
IF b_paragraph_started AND buffer LIKE '%DE4%' THEN
utl_file.put_line(outfile,buffer, FALSE);
END IF;
--ENDPOINT APPLICATION
IF buffer LIKE 'ZEN%' THEN
b_paragraph_started := FALSE;
END IF;
utl_file.fflush(outfile);

EXCEPTION
WHEN no_data_found THEN
EXIT;
END;
END LOOP;
END IF;
utl_file.fclose(infile);
utl_file.fclose(outfile);
EXCEPTION
WHEN OTHERS THEN
raise_application_error(-20099, 'Unknown UTL_FILE Error');
END my_app2;
/

When I run this code I only get one line: DE4.2 I AM MISSING THE ENTIRE PARAGRAPH

PLEASE ADVISE...