this may be to a permission issue.
Open the Finder, locate this folder:
Do a right-click onto, or [Cmd]+I, then select "Get Info".
Change the rights to "Read & Write" for every user on the machine.
Apply the changes by clicking on the gear icon: "Apply to enclosed items"
If your Spark Library folder is located elsewhere please do the same thing for it.
LEt me know if this solves your issue.