class file has wrong version 50.0, should be 49.0

I was compiling a java file in Rel12 environment. i got following error
<my java filename>:<line number in the file>: cannot access oracle.sql.BLOB
bad class file: <file path>/appsborg.zip(oracle/sql/BLOB.class)
class file has wrong version 50.0, should be 49.0
Please remove or make sure it appears in the correct subdirectory of the classpath.
import oracle.sql.BLOB;


Reason for this error was older version of javac. when i compiled my java file, javac from /usr/bin was used and it's version was 1.5.0_24.

when i compiled java file from jdk bin directory, it compiled successfuly. version of javac in jdk/bin was 1.6.0_10