Continue Test Suite in Test Suite Collection on same browser

I have:
Test case:
TC1- log in to demo-herokuapp. - works with no errors
TC2- enter values and book appointment. - works with no errors when execute with previous opened browser from TC1
Test suite:
TS1 - just one test case TC1
TS2 - just one test case TC2
Test suite collection:
TSC - TS1 and TS2
When execute TSC the TS2 fails with error :
Caused by: com.kms.katalon.core.webui.exception.BrowserNotOpenedException: Browser is not opened
Build info: version: ‘3.7.1’, revision: ‘8a0099a’, time: ‘2017-11-06T21:07:36.161Z’
System info: host: ‘TK-PC’, ip: ‘10.1.10’, os.name: ‘Windows 10’, os.arch: ‘amd64’, os.version: ‘10.0’, java.version: ‘1.8.0_181’
Driver info: driver.version: unknown

Note: settings : Terminate drivers after each Test Case and Terminate drivers after each Test Suite are uncheck

Any suggestions would help.
Thanks