Try the following tips if you are unable to continue through the game:
- Scan the level to ensure that you have defeated all enemies.
- Move to any fence, wall, ladder, scaffolding, or roof edge until a yellow glow appears. Interact with the glowing object (the A button on Xbox or the X button on PS3).
- Restart from your last checkpoint by selecting Restart from Checkpoint in the Pause Menu
- Restart the level by selecting Restart Level in the Pause Menu
- Return to HQ by selecting Return to HQ in the Pause Menu