Creating EM12c O.S. Job for data pump --> How to pass %Service Name% to the shell script

Update:  The screen shot of EM job definition is below:

I have a O.S. shell script that does RAC database full export by passing in the Cluster Managed Service name. 

It works perfectly at command line or cron.

I tried to schedule this shell script as an OEM 12c O.S. job.  But EM job failed to invoke expdp, just flies by and did nothing.

Can someone kindly help?  Maybe I used %Service Name% the wrong way?

Many thanks!  Joy

Below is the info.

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Release:                                            EE/GI 12c 2-node RAC on Exadata

Database:                                          xseed

Cluster Managed Service Name:      xseed_dp