Make the text in the second keyframe a movie and call the movie fadein.
Then right click on the movie and do a simple fade in to the text and adding a stop action to the last keyframe.
Your movie should look something like the picture below. (I suggest in 5 frames or less).
After you finish that add go back to the over movie and make make the text in frame three into a movie called fadeout (make sure you add a stop action the last keyframe). This time making the movie fade out.
Then go back to the over movie and add a stop action to each frame.
Your movie should now look similar the picture below.