Premiere Elements 12 SmartMix problem

Hello,

Whenever I am using the Smart Mix tool to automatically adjust my soundtrack to fade behind my Audio 1, it gives me the following message:

"Cannot perform SmartMix. Missing dialog in the foreground track."

I am not sure how to get around this, And I dont know how to adjust my soundtrack volume to fade down when my Audio 1 starts and fade back in when it ends. Any help would be greatly appreciated.