Invoke Scheduled Job on demand in SQL Server by serverku

We are mostly scheduled the job for the any script, but I have prepared the SP which invoked Job on demand as required, below code which I have created by SP and called it from the UI.

USE MSDB
GO

DECLARE @JobName VARCHAR(100)  
SET @JobName = 'YourJobName'

EXEC MSDB.DBO.Sp_start_job @JobName  --You can also invoke with JobId
GO

When you run it gives message, "Job 'YourJobName' started successfully." On second run, if first request is in queue, it will return with the following message, "Msg 22022, Level 16, State 1, Line 0 SQLServerAgent Error: Request to run job YourJobName (from User sa) refused because the job already has a pending request from User sa."