Can't install app to android device

When I select an Android project from the project tree to the left, and then right click and select "Install to Android Device" the installation fails with the following error:

...
[INFO] Compiling localization files
[ERROR] Exception occured while building Android project:
[ERROR] Traceback (most recent call last):
[ERROR] File "/Users/uno/Library/Application Support/Titanium/mobilesdk/osx/3.1.0.GA/android/builder.py", line 2553, in <module>
[ERROR] builder.build_and_run(True, avd_id, device_args=device_args, debugger_host=debugger_host, profiler_host=profiler_host)
[ERROR] File "/Users/uno/Library/Application Support/Titanium/mobilesdk/osx/3.1.0.GA/android/builder.py", line 2264, in build_and_run
[ERROR] self.manifest_changed = self.generate_android_manifest(compiler)
[ERROR] File "/Users/uno/Library/Application Support/Titanium/mobilesdk/osx/3.1.0.GA/android/builder.py", line 1404, in generate_android_manifest
[ERROR] '-I', self.android_jar], warning_regex=r'skipping')
[ERROR] File "/Users/uno/Library/Application Support/Titanium/mobilesdk/osx/3.1.0.GA/android/run.py", line 38, in run
[ERROR] print "[DEBUG] %s" % subprocess.list2cmdline(args_to_log)
[ERROR] File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 587, in list2cmdline
[ERROR] TypeError: argument of type 'NoneType' is not iterable
[ERROR] : Build process exited with code 1
[ERROR] : Project failed to build after 1s 809ms

The project runs OK in the iPhone Simulator