Concatenate two strings to make a path?

Hi guys! I have a little problem and would be very greatful if you would help me out, i have a deadline in who days =( … i have a function that looks like this:

function laddaBild(laddamig:String, projekt:String){
_root.workplate_mc.randwork2_mc[“preloader”+laddamig+"_mc"].target.loadMovie(this.url);

}

[color=Green]this one works fine, the problem is that i want to get the value function to replace the number two at the randwork2_mc path… i have tried the following two solutions:[/color]

[color=Red]ONE

[/color]function laddaBild(laddamig:String, projekt){
[color=SeaGreen][/color]_root.workplate_mc[“randwork”+projekt+"_mc"][“preloader”+laddamig+"_mc"].target.loadMovie(this.url);
[color=SeaGreen]// I have been trying many combinations for this one, with dots before and after etc but with no luck…[/color]

}
[color=Red]TWO

[/color]function laddaBild(laddamig:String, projekt){
temppreloadpath = “preloader”+laddamig+"_mc.";
concLoadPath = “randwork”+projekt+"_mc."+temppreloadpath;
trace(concLoadPath);
[color=SeaGreen]// the tracing works fine here but i dont know how to concatenate below (if its even possible)[/color]
_root.workplate_mc.concLoadPath.target.loadMovie(this.url);
[color=SeaGreen]// ok this doesnt work, concLoadPath is undefined[/color]

}

Got any ideas? Im desperate here =)