Kill Process

Sometimes it worked killing chrome, and sometimes don't, do you know why this happens?

Here the resulting logs of the failure. 

=> [Debug] Debug started for file: Main

=> [Info] 55_Blackline JE Upload Support execution started

=> [Debug] Killing processes...

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Info] Process Name: chrome, User Name: US\RTREVINO1

=> [Error] Kill Chrome process user wise: Exception occurred during the killing process.

Thanks in Advance

Can't kill the process ,process name "iexplore", user name "s41586" , can know why ?