Data Currently Locked by another user Error!!!!

Hello Everyone;

Wish all a great day!!!

I am running over a scenario and kindly requesting help from my fellow Forum Mates. In my project over a process to avoid data during middle of entering something like in a Invoice Billing Window i have set up two nodes- One at starting and other at the end if the chain breaks before reaching the end node i have made some codes to roll back the entire process again back to original state. In all my projects this works perfect but over a mass user project i get back this error. Could anyone help me out with this error. SCREENS attached.

This is the inline code:

HTransactionStart(gsDbConnetion)
WHEN EXCEPTION IN

HTransactionEnd(gsDbConnetion)
DO
//Roll back
HTransactionCancel(gsDbConnetion)
Error("Save has been failed")
END