Select list item: Attempt to get item number 1 of a list of length 0: ()

I got a problem using the TinyWebDB in App Inventor 2. Here's a Screenshot of the blockcode.

And it keep appear the error:

select List Item: Attempt to get item number 1 of a list of length 0:()

How can we solve this problem? 

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The program is saying that you are trying to get item number 1 from a list of length 0, i.e., from an empty list.

Looking at your blocks, I'd guess that the list Waittime is empty.  And I'd guess it is empty because the value coming from TinyWebDB is empty.
but that's ust a guess.   you can verify this yourself  by using DOIT.

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