FWIW, it looks as if the the AppStore version of OmniFocus is unable to run a number of scripts on these forums which the non-AppStore version is able to run without any problem.
This is because its seems that the AppStore versions may have a different "bundle identifier", e.g.
If this is the general pattern with AppStore versions then the form of reference to applications which Apple has recommended since OS X 10.5 will not be transferable between shelf and AppStore versions of Omni products
tell application id "com.omnigroup.omniplan"
might have to be edited to something like:
tell application id "com.omnigroup.omniplan.macappstore"
Unless the 4-letter creator codes for an app also now vary between directly purchased and Appstore versions of Omni apps, the simplest and most durable edit might be to replace the long bundle identifiers with the short creator codes, which Applescript will also recognise.
tell application id "OFOC" -- OmniFocus
tell application id "OOut" -- OmniOutliner
tell application id "OPla" -- OmniPlan
tell application id "OGfl" -- OmniGraffle
Creator codes can be discovered by running a snippet like:
tell application id "sevs"
creator type of (application processes where name contains "Omni")
(Where sevs is the creator code for "System Events", otherwise known as "com.apple.systemevents")