How to increment transaction number

Hi, i have created a transaction number with datetime + an integer variable and have the default value of the integer set to 1.

I’m trying to increment the number with every transaction, and I’ve tried placing an assign activity at the end with integer variable = integer variable +1, but everytime the transaction is ran, it goes by to 1.
how do i increment it?

Yea it correct only. Can you check the xaml are you changing the Value again to 1.

Else upload ur xaml file