Bitmpadata hitest crash

1

when I use this hittest my program crashes?

The paramaters I have tested exist and it is simply 2 bitmaps.

enemyItem=myEnemy.getEnemy;
myimg=enemyItem[0].img;
bmpdata=myimg.bitmapData;

if(   bmpdata.hitTest(new Point(myimg.x, myimg.y),  255, 
                                      myplayer.img.bitmapData,
                                       new Point(myplayer.xVal, myplayer.yVal),
                                       255))