Need Help on installation

Hi
I have some trouble on installation.

I am setting up the RelEx under cygwin in windows. I installed all necessary packages, and change the path in the build.xml .

When I compile it is showing the following errors:

[TiTiShih@TiTiLap ...RelEx/relex-0.98.0]$ ant
Buildfile: build.xml

build-subprojects:

init:

build-project:
     [echo] relex: f:\RelEx\relex-0.98.0\build.xml
    [javac] Compiling 125 source files to f:\RelEx\relex-0.98.0\bin
    [javac] javac: invalid target release: 1.5
    [javac] Usage: javac <options> <source files>
    [javac] where possible options include:
    [javac] -g Generate all debugging info
    [javac] -g:none Generate no debugging info
    [javac] -g:{lines,vars,source} Generate only some debugging info
    [javac] -nowarn Generate no warnings
    [javac] -verbose Output messages about what the compiler
is doing
    [javac] -deprecation Output source locations where deprecate
 APIs are used
    [javac] -classpath <path> Specify where to find user class files
    [javac] -sourcepath <path> Specify where to find input source file

    [javac] -bootclasspath <path> Override location of bootstrap class fi
es
    [javac] -extdirs <dirs> Override location of installed extensio
s
    [javac] -d <directory> Specify where to place generated class
iles
    [javac] -encoding <encoding> Specify character encoding used by sour
e files
    [javac] -source <release> Provide source compatibility with speci
ied release
    [javac] -target <release> Generate class files for specific VM ve
sion
    [javac] -help Print a synopsis of standard options
    [javac]

BUILD FAILED
f:\RelEx\relex-0.98.0\build.xml:61: Compile failed; see the compiler error outp
t for details.

Total time: 0 seconds

I am not sure where went wrong, is it because of the Java version? What does it mean for " invalid target release: 1.5" ?
Any guidance would be very appreciate.
Thank you
Chih-Ti