Why is the 'Back' button and/or 'slider' disabled?

In PerfectIt 3, you can go back and review the previous error within one of PerfectIt's checks by clicking the 'Back' button. However, the 'Back' button only moves within a check, not to a previous check. For example, it will move back within the check of 'Phrases in Capitals', but will not go back to the check for 'Abbreviations Without Definitions'. As a result, when PerfectIt is at the start of a check, the 'Back' button is disabled or greyed out.

The slider is located just below the 'Back' button. You can use it to move quickly back and forth through all the errors in one check. It will be greyed out or disabled if there is only one error in a check.