Nested If...Then...Else Syntax Error

[DeathSheep]

I'm trying to adjust the list name of a power based on the character's level. Whenever I try to test the script, I get an error "Expected '(' following 'if' or 'while' statement. I don't see any syntax errors in the code, so I'm hoping someone else's eyes can catch what I'm not seeing.

     if (field[xAllLev].value >= 17) then
        field[listname].text = field[thingname].text & " (d12)"

      elseif field[xAllLev].value >= 13) then
        field[listname].text = field[thingname].text & " (d10)"

      elseif (field[xAllLev].value >= 9) then
        field[listname].text = field[thingname].text & " (d8)"

      elseif (field[xAllLev].value >= 5) then
        field[listname].text = field[thingname].text & " (d6)"

      else
        field[listname].text = field[thingname].text & " (d4)"
      endif

The error is reported on line 2.