I have the following timeline:

<clip1-8secs><clip2-3secs><clip3-3secs><clip4-3secs><clip5-20secs>

I wish to have a short fade between clip2 and clip3 but when I try to use the Cross Dissolve transition in Adobe Premiere Pro CS3, I get a message stating "Insufficient media. This transition will contain repeated frames."

Any idea how I can solve this?