the "Adjust composition duration to the time span of the selected layers" in the Pre-Compose dialog box was only introduced in CC. if you are in CS6 and you want to Pre-Compose to the duration of the Layer you have to take the long route which is this:
1. your layer needs to be trimmed like this
2. while the layer is selected you type Cmd+Alt+B so the work area be trimmed to the layer like this:
3. you Pre-Compose with these settings:
4. in your pre-comp you right click on the work area and select "Trim Comp to Work Area"
5. you get back to your master comp and feel happy with what you have accomplished
This is beautiful thank you a million!
you're welcome! thank you for the feedback and making my comment greenish.