Why does this not work

[Luffy123]

I got this from the turing documentation.

code:

var howMany : int get howMany var height : array 1 .. howMany of real function total (a : array 1 .. * of real) : real     var sum : real := 0     for i : 1 .. upper (a)         sum := sum + a (i)     end for     result sum end total put "Sum of the heights is ", total (height)

I dont' understand why it doesn't work. The error I get is

sum := sum + a (i)

Variable has no value in this line

[Amarylis]

Look carefully at the code: Which one of the two in that line do you know already has a value, sum, or a (i)?