With switches the cases can’t be variables but instead arguments, hence why it doesn’t work when you put the name of the variable in because it sees it as a string. But it will work when you 19/04/2019 as a string as the case.
Can i have a view on the switch case if possible a screenshot and the variable mystring1 declaration as well
Or Try to mention the value in the case without double quotes
that would be the issue i guess as it should work for sure
Fine usually i hope we give only in case where the expression has the variable or arguments…so that could be the issue, I tried to reproduce this issue from side, variable in the case didn’t work, only value when passed to case it works…i tried to figure out whether it is correct or not in microsoft docs as well