Custom scripts cannot run

Custom scripts cannot run

I am using Opmanager build  9101, and tried to run a built-in custom script (script names "File Size") on a Linux CentOS5 server, and got error: Exit code: 4, Message File Size:Unable to connect: Connection refused: connect. I tested server SSH credential (by clicking on password link) and it was OK. Many ideas were tested but still not work.
Please help me, thanks very much.

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