You should check your identification against the information that can be obtained by pressing the "Information" button, in the "Taxa" toolbar (top-right pane). The information usually includes full and diagnostic descriptions. A diagnostic description aims to distinguish the taxon from all the others, using only characters that have not already been used in the identification. Illustrations may also be available.
If the descriptions or illustrations are inconsistent with the tentative identification, you can increase the "error tolerance", by means of the "Error tolerance" button in the "Characters" toolbar (in the top-left pane). This allows a greater number of mismatches before taxa are eliminated, so some taxa that were previously in the "Eliminated Taxa" pane move to the "Remaining Taxa" pane. The identification process can then be continued exactly as before, until only a single taxon remains.
Increasing the error tolerance may also be used directly to confirm or increase your confidence in a tentative identification. Continuing the identification after increasing the error tolerance should again lead to a single remaining taxon. This may or may not be the same as the original remaining taxon, but, in either case, it will be more strongly separated from the eliminated taxa, and so you can have more confidence in the result. The advantage of this method over using a diagnostic description is that you have full control over the extra characters used.
In Advanced mode (see "Help" menu), an increased error tolerance can be used in conjunction with the "Separate a given taxon" button, which orders the available characters according to how well they separate a given taxon from the other remaining taxa. This can lead to a quicker confirmation or rejection of the tentative identification. If the extra information that you enter is inconsistent with the original identification, you should switch back to using the "Best" order.