Please try the following:
- Go to the MAIN PAGE.
- Use the BLOCK arrows to highlight the EXP block.
- Press the OK button. This should turn on the block.
In addition, you might want to check the "Range" parameter on page 2 of the Expander. This parameter sets the amount of damping. In order for the Expander to work, the "Range" parameter must be different from 0 dB.