In call to function My_sum, the first parameter, X, should be in ascending order.
You have called a function that requires the values in the array passed to the parameter to be in ascending order, but the values in the array were not in ascending order.
For a function parameter declared as follows,
Function My_sum(X : ascending)
calling the function as called below would trigger this error as the array passed is not in ascending order.
My_sum([4, 1, 7])
Pass an array with values in ascending order as the indicated parameter to the function.
You can use the Sort function to sort an array in ascending or descending order.