From Birnam Designs Wiki

When a task whose path has spaces or other characters that require the path to be in quotation marks is added to schtasks, it will not run because the processor took the initial quotes as delimiters of the parameter, not literally. In order to get this to run correctly an additional \" must be added within the quotes.

incorrect schtasks /create /tn "my task" /tr "c:\foldername containing spaces\script.bat arguments" /sc once /sd 07/29/2003 /st 10:01

correct schtasks /create /tn "my task" /tr "\"c:\foldername name containing spaces\script.bat\" arguments" /sc once /sd 07/29/2003 /st 10:01