Remove the storeId from your store. It is automatically generated from the className of your store. So your 'test.store.ServiceType' store would be available using 'ServiceType' (just like you define in your app.js):
@rdougan: That's not right! Maybe it should be so, but I debugged "sencha-touch-all-debug.js" and it isn't.
If you don't add a storeId, there will be generated something like "my-package-storename-1". If you try to get the store by Ext.getStore('Storename'), this won't return a result, because in the manager there is no such id in the map (there you can only find the generated long version)!
So I looked at your code again and it seems that the problem is that you are giving a 'config' block where you create your selectfield.
config blocks are only used when you use Ext.define to create a new class. If you are creating an instance of a class which already exists (using Ext.create, or using a simple block object like you have with selectfield), you put the configuration options in the object itself.