Error on Ant Saying: Error occurred during initialization of VM?

Hi am running LingPip on Ant and am getting these errors. Can some one help me??

C:\LingPipeDir\lingpipe-3.8.1\demos\tu… -Dsenseval.dir=c:\$senseval-en run

Buildfile: C:\LingPipeDir\lingpipe-3.8.1\demos\tuto…

compile:

jar:

run:
[java] Could not create the Java virtual machine.
[java] Error occurred during initialization of VM
[java] Could not reserve enough space for object heap
[java] Java Result: 1

BUILD SUCCESSFUL
Total time: 2 seconds

I tried Changing the java heap size using the following commands:
set ANT_OPTS="-Xms512m -Xmx512m"
But am still getting the same set of errors.