When you create an unsigned symbian package, the package will be named with the pattern %appname%_installer_unsigned.sis

However, if you try to execute the Run action with unsigned .sis, you get an error like this:

:-1: error: Failed to find package 'D:/workspace/myapp/myapp_unsigned_installer.sis': Package file not found

Which obviously doesn't exist since the words unsigned and installer are flipped.