GetSelectedCount() is used to determine the number of selected values in a field. The expression you provided includes a conditional statement using the IF() function, which will return a Boolean value (either True or False) depending on the result of the condition.
If the result of the condition is True, then the GetSelectedCount() function will be executed and its result will be compared to zero. If the result is greater than zero, then the entire expression will evaluate to True. Otherwise, it will evaluate to False.
However, if the condition in the IF() function is not met and returns False, the GetSelectedCount() function will not be executed, and the expression will return -1. This value indicates that the function could not be evaluated due to the condition being false.
Therefore, it is important to make sure that the condition in the IF() function is correctly formatted and will not result in a False output in order to prevent the GetSelectedCount() function from returning -1.
