Ball game - Error #1010

1

Hi!
I just started a course in Flash so I’m somewhat a newbie. I’m sorry the answer is obvious and I’m a bother :<
In the game you are rewarded a point if you catch the green ball (pointer) and it’s game over if you touch a red one (enemy). If you reach 5 points you advance to the next level and another enemy will spawn. And that’s when this error occurs:

TypeError: Error #1010: A term is undefined and has no properties.
at Bollspel_fla::MainTimeline/enemiesMove()[Bollspel_fla.MainTimeline::frame2:58]
at Bollspel_fla::MainTimeline/eachFrame()[Bollspel_fla.MainTimeline::frame2:16]

stop()
var points:int = 0
var level:int = 0
var fiender:int = 1
var riktningX:Array = new Array (1)
var riktningY:Array = new Array (1)

stage.addEventListener(Event.ENTER_FRAME,eachFrame)

function eachFrame(e:Event){
    minBoll.x = mouseX
    minBoll.y = mouseY
    
    // Move each enemy
    for(var i:int = 0; i <= level; i++){
        enemiesMove(i)
    }
    
    // Catch a point
    if(minBoll.hitTestObject(pointer)){
        points = points + 1
        pointer.x = Math.random() * (550 - pointer.width / 2)
        pointer.y = Math.random() * (400 - pointer.width / 2)
        if(points % 5 == 0){
            level = level + 1
        }
    }
    pointCount.text = "Poäng: "+points
    levelCount.text = "Nivå: "+level
}

// Add an enemy
function addEnemy(e:MouseEvent){
    var enemy:Fiende = new Fiende()
    this.addChild(enemy)
    enemy.x = 25;
    enemy.y = 45;
    enemy.name = "fiende"+(level)
    riktningX.push(1)
    riktningY.push(1)
}
    

// Move an enemy
function enemiesMove(whatEnemy){
    var xpos:int = riktningX[whatEnemy]
    var ypos:int = riktningY[whatEnemy]
    var enemy:String = "fiende"+whatEnemy
    
    // Move an enemy left or right until it hits the edge
    if(xpos == 1){
        this[enemy].x+=10
        if(this[enemy].x > 550 - this[enemy].width / 2){
            riktningX[whatEnemy] = 0
        }
    }
    else if(xpos == 0){
        this[enemy].x-=10
        if(this[enemy].x < 0 + this[enemy].width / 2){
            riktningX[whatEnemy] = 1
        }
    }

    // Move an enemy up or down until it hits the edge
    if(ypos == 1){
        this[enemy].y+=10
        if(this[enemy].y > 400 - this[enemy].width / 2){
            riktningY[whatEnemy] = 0
        }
    }
    else if(ypos == 0){
        this[enemy].y-=10
        if(this[enemy].y < 0 + this[enemy].width / 2){
            riktningY[whatEnemy] = 1
        }
    }
}

// Game is over
function gameOver(){
    stage.removeEventListener(Event.ENTER_FRAME,eachFrame)
    gotoAndStop(3)
}