I was trying to download an app called "gpiomonitor" thru the pistore. It downloaded the second time, but would never launch. Finally I figured it out - its mentioned in the app details that you need to run the app with root privileges. However, a simple "sudo pistore" does not work, at least over vnc, since it cannot connect to the X-server. (stupid linux problems)
What you have to do is use: "gksudo pistore". Install the relevant package and then it should run.
Alternatively, if you want to run the the app directly, type this:
>gksu python /usr/local/bin/indiecity/InstalledApps/gpio-monitor/Full/GPIO_Monitor/gpiomonitor.py
NB: I still haven't figured out what it does though, apart from listing the ports at start up
NB 2: The app runs from console. However, pistore may freeze when running with root privileges, showing a black screen instead. No idea as yet, why.