Second effect: Set exactly as below but make sure you choose your trigger object first from the 'trigger object' drop down box or a dialogue box will appear to ask you if you would like to make changes to the first effect you just set, when done then press the 'apply' button then press the 'ok' button.
Now your done, you can now press the preview button and see your linear colored box in action.
Tip: if you want to group the text box with the gradient rectangle, make sure you place the created 'group object' before all other objects within the group in 'Z Positioning', or the 'gradient rectangle' might hide the 'text box'.