Try following.
<exec executable="D:/enlil/glassfish3/bin/asadmin" failonerror="true">
<arg value="--passwordfile"/>
<arg value="D:/stajyer/password.txt"/>
<arg value="deploy"/>
<arg value="--contextroot"/>
<arg value="/GlassfishDeployment"/>
<arg value="dist/MobilHis.war"/>
</exec>
Keep arguments in separate <arg/>
elements.
This is probably because glassfish not being able to open up the command prompt.