I think the job is queued? There will only be a log when the job is started.

Yes it’s queued, but when I click on on the workspace, it shows the error  (The log file for job ID "6" does not exist.) which I have tried it many time.

Not sure if I understand your question, but I think you want to know why server does not start processing the job.

On the left side of the screen, engine management, engines. Do you have any active engine?

I have not setup the engine at the left-hand side, I think I need to do that.

could the Engine be the cause of the error ​@nielsgerrits 

It is not really an error, but yes, without an engine, FME server will not process a job.