Is it Possible to Decrease in Salary on Promotion from Lower to Higher Scale?

This is a strange question for many people but it is the reality that there may occur a Decrease in Salary on Promotion from Lower to Higher Scale in some cases. Sometimes the promotion of some employees occurs and they face a strange situation of salary fixation. During the fixation of pay from lower to higher pay scales, it was found that the salary of the employee was reduced instead of enhanced in pay and allowances. I shall explain the situation with an example.