Hi Mark,
I completely agree with you the concept you explained above. I can't unapply a transaction which has already been applied.
But the above screen shot shared by me has a previous button, here I am also using the same loop over displayed items as Bala. I am curious to know why there is a difference in the behaviour for the same action.
I look forward to your valuable advices to help me to understand this concept.
Thanks,
Sudhir.