Why dis code don´t make another rows(FMX2004)

[jupiter]

function addMovieThumbs() {
	for (var i = 0; i<=thumbText.length-1; i++) {
		var thumbs = attachMovie("thumb", "thumb"+i, this.getNextHighestDepth());
		thumbs._x = 0+(thumbs._width+dixt)*i;
	   
		thumbs._y = 13;
		thumbs.title_txt.text = thumbText*;
		thumbs.mc = moviesLoad*;
		if (thumbs._x>=780) {
		 
			thumbs._x = 0;
			thumbs._y = 130;
			//b += 130;
		}

	}
}

the movies go the next row but they stay all in the same x location

please can someone help