Hi Sreeni,
You are still using the old transactions.
When you had upgraded your system? I guess you had created the new project and activate the charm there as by default it will activate with the SM* transactions, however your old project is still using SD* transactions.
Please make sure before you creating any maintenance project cycle , including the new project (maintenance) in /tmwflow/switch.
For more information check below
Change Request Management scenario: Usual questions and known errors
Regards
Rishav