Calling a custom package

[tlmarker]

I am having problems calling a custom package. I have a package defined as follows:

package MMES {
	/**
	 * Global import commands
	 */
	import flash.display.*;
	import flash.events.*;
	import flash.net.*;
	
	/**
	 * Common Class definition
	 * This class contains methods used by some/all of the MMES Flash Programs
	 * @extends MovieClip
	 */
	public class Common extends MovieClip {
		/**
		 * Constant defintions
		 */
		public const WEBSITE:int = 0;
		public const SUBMIT:int = 1;
		public const UPDATE:int = 2;
		var configFile:Array;
		var myLoader:URLLoader;
		var filePath:String;
		var myReq:URLRequest
		var loaded:Boolean = true;

		var myArrayOfLines:Array;
		/**
		 * Class Constructor
		 * @param	void
		 * @return	int
		 */ 
		public function Common():void {
			filePath  =  "config/MMESCommon.cfg";
			myReq  =  new  URLRequest(filePath);
			myLoader  =  new  URLLoader();
			myLoader.addEventListener(Event.COMPLETE,  fileLoaded);
			myLoader.addEventListener(IOErrorEvent.IO_ERROR,  ioErrorHandler);
			try {
				myLoader.load(myReq);     
			}      
			catch (error:Error) {
				loaded == false;
			}
			trace(loaded);
		}
		/** Method to return the load status
		 * @param void
		 * @return The Boolean load status
		 */
		public function loadStatus():Boolean {
			return loaded;
		}
		/**
		 * Method to calculate a numeral score
		 * @param	correct:int
		 * @param 	possible:int
		 * @return	The numeric score earned
		 */
		public function numericScore(correct:int, possible:int):int {
			return int((correct / possible) * 100);
		}
		/**
		 * LetterScore function
		 * @param	score:int		The numerial grade earned
		 * @return  retval:String: 	The letter grade earned
		 */
		public function letterScore(score:int):String {
			var retval = "";
			if (score >= 90 && score <= 100) {
				retval = "A";
			} else if (score >= 80 && score <= 89) {
				retval = "B";
			} else if (score >= 70 && score <= 79) {
				retval = "C";
			} else if (score >= 60 && score <= 69) {
				retval = "D";
			} else if (score >= 50 && score <= 59) {
				retval = "F";
			} else {
				retval = '--';
			}
			return retval;
		}
		/**
		 * submitScore Function
		 * @param	uname:String	The students name
		 * @param	pScore:int		The students past score
		 * @param	rid:int			The resource id
		 * @param	lid:int			The lesson id
		 * @param	cscore:int		The current score
		 * @return	void
		 */
		public function submitScore(sid:int, rid:int, lid:int, cscore:int, pScore:int):void {
			var postScore:URLRequest;
			var postAddress:String
			var postData:String = sid + "/" + rid + "/" + lid + "/" + cscore;
			if (pScore == 0) {			
				postAddress = configFile[WEBSITE] + configFile[SUBMIT] + postData;
			} else {
				postAddress = configFile[WEBSITE] + configFile[UPDATE] + postData;
			}
			trace("Post Address: " + postAddress);
			//postScore = new URLRequest(postAddress);
			//navigateToURL(postScore);
		}
		/**
		 * Call back function for when file is loaded
		 * @param	e:Event
		 * @return	void
		 */
		public  function  fileLoaded(e:Event):void {
			configFile = e.target.data.split(/\n/);
			configFile[WEBSITE] = trim(configFile[WEBSITE]) + "/";
			configFile[SUBMIT] = trim(configFile[SUBMIT]) + "/";
			configFile[UPDATE] = trim(configFile[UPDATE]) + "/";
		}
		/**
		 * Call back function for a file error
		 * @param	e:IOErrorEvent
		 * @return 	void
		 */
		public  function  ioErrorHandler(e:IOErrorEvent):void    {
			trace("There  was  a  problem  loading  a  " + filePath + "  file:  " + e);
			loaded = false;
		}
		/**
		 * Function to trim the whitespace from a string
		 * @param	s:String
		 * @return  String representing s without whitespace at the right end
		 */
		function trim( s:String ):String
		{
			return s.replace( /^([\s|\t|\n]+)?(.*)([\s|\t|\n]+)?$/gm, "$2" );
		}
	}
}

The class file(Common.as) is save in the MMES directory which is a subdirectory of the root directory containing the main class file.

I am tring to call this from a main program as follows:
First I import the class file

import MMES.Common

I then create an instance:

var MMES:Common = new Common();

Lastly I try to call a function of the custom class:

letterGrade.text = MMES.letterScore(MMES.numericScore(correct,count));

However, for every call to a method in the Common class I get:

1180: Call to possibly undefined method

I have been researching this problem, but have been unable to get it working. Any help would be greatly appreciated.
Thanks, Troy.

[dawsonk]

package {

        import flash.display.*;
        import flash.events.*;
        import MMES.Common;

        public class Main extends Sprite {

                public function Main() {
                        var correct = 10;
                        var count = 10;
                        var mmes:Common = new Common();
                        letterGrade.text = mmes.letterScore(mmes.numericScore(correct,count));
                }
        }
}