Here is some smaller/cleaner code that should perform the task just fine. Let me know how it works out. This code should be NoVarInStrings compliant.

Copy the code and paste it to Wordpad, then copy it from Wordpad and paste it to notepad or other text editor and save the file.

NOTE This is basically the code that Les and Shawn laid out for you already. I simply placed it into a full working code example.

Code:
Break On

Dim $SO,$Folder,$File,$FileList

$SO=SetOption('Explicit','On')

$SO=SetOption('NoVarsInStrings','On')

$Folder='C:\FOLDERA\'

$FileList='file1.txt','file2.txt','file3.txt','file4.txt','file5.txt'

  

For Each $File In $FileList

  If Not Exist($Folder + $File)

    Shell  '%COMSPEC% /C C:\kix\WZUNZIP.exe -e ' + $Folder + 'isafile.zip ' + $File + ' ' + $Folder + ' >NUL 2>NUL'

  EndIf

Next


SPACING OF QUOTES IS IMPORTANT