how to use dirSize() EL function in oozie decision node - el

Question

I tried to use dirSize() in oozie decision node. but it does not work.
When I use ${fs:dirSize(InputDir) gt 10 * KB} in the decision node. The oozie workflow status moves to failed state and no error is displayed.
Please find below the code snippet from workflow.
<action name="L1_check" cred="hcat_creds">
<hive xmlns="uri:oozie:hive-action:0.2">
<job-tracker>${jobTracker}</job-tracker>
<name-node>${nameNode}</name-node>
<script>l1_check_code.sql</script>
<param>PI_DB=${PI_DB}</param>
<param>PRD_DB=${PRD_DB}</param>
<param>PROMO_START_DATE=${PROMO_START_DATE}</param>
<param>PROMO_END_DATE=${PROMO_END_DATE}</param>
</hive>
<ok to="decision-node" />
<error to="fail" />
</action>
<decision name="decision-node">
<switch>
<case to="L1_exists">
${fs:dirSize(InputDir) gt 10 * KB}
</case>
<default to="fail"/>
</switch>
</decision>
InputDir is a defined in the properties file and the path exists.
First action L1_check executes and transitioned to decision node. then workflow status changes to Failed state.
Is there any error in the way function is used? If yes, what should be right function to use?
Also is there a way to give a path with combination of parameter and string
eg: dirSize(InputDir/l1_check)
where InputDir is a parameter and l1_check is a static name