Auto-Fill using TextBox - google-apps-script

Question

I had this working using a listbox, but now I want to change it to a textbox and I keep getting the error: "Error encountered: Cannot read property "1" from undefined." I am not sure of the issue. I had this same code working with a listbox and just tweaked it. I am needing help to solve the problem and wondering if I am down the wrong path.
EDIT - ERROR OCCURANCE
The error occurs when I put in a Student ID Number on the form, that references a Google Spreadsheet. When I hit Enter, I get the error and nothing auto-fills the other fields I have setup.
Form Build (part)
//Create the form elements
//Set DateBox to Today's Date
var date = new Date()
var txtDate = app.createTextBox().setName("txtDate").setId("txtDate").setValue(Utilities.formatDate(date, 'America/New_York', 'MM/dd/yyyy | hh:mm a')).setReadOnly(true).setEnabled(false).setStyleAttributes(lockedStyle);
var lblStudentNumber = app.createLabel('Student ID#:');
var hdlStudentInfo = app.createServerHandler('getStudentInfo').addCallbackElement(vrtMainPanel);
var lbxStudentInfo = app.createTextBox().setId('lbxStudentInfo').setName('lbxStudentInfo').addChangeHandler(hdlStudentInfo).addChangeHandler(alertHideHandler);
// var txtStudentNumber = app.createTextBox().setName("txtStudentNumber").setId("txtStudentNumber").setReadOnly(false).setEnabled(true).setStyleAttributes(normalStyle);
var lblStudentName = app.createLabel('Student Name:');
var txtStudentName = app.createTextBox().setName("txtStudentName").setId("txtStudentName").setText("Student Name").setReadOnly(true).setEnabled(false).setStyleAttributes(lockedStyle);
getStudentInfo Function
function getStudentInfo(e){
var spSheet = SpreadsheetApp.openById('1OhR5i8B89uK7XXW2Izdzim0LSngSr6KQPqL5ToeZTbo');
var spStudentList = spSheet.getSheetByName('Schedule');
var lstStudentID = spStudentList.getRange(2,1,spStudentList.getLastRow(),18).getValues();
var app = UiApp.getActiveApplication();
// var currTime = new Date();
// var formattedTime = Utilities.formatDate(currTime,"hh:mm a");
var txtStudentName = app.getElementById('txtStudentName');
var txtTeacherName = app.getElementById('txtTeacherName');
// var txtExt = app.getElementById('txtExt');
var txtEmail = app.getElementById('txtEmail');
var txtPeriod = app.getElementById('txtPeriod');
var txtSubject = app.getElementById('txtSubject');
txtStudentName.setText(lstStudentID[e.parameter.lbxStudentInfo][1] + " " + lstStudentID[e.parameter.lbxStudentInfo][2]);// sets Student's Name
txtPeriod.setText("1st Period");// sets Period
txtSubject.setText(lstStudentID[e.parameter.lbxStudentInfo][6]);// sets Subject
txtTeacherName.setText(lstStudentID[e.parameter.lbxStudentInfo][7]);// sets Teacher's Name
txtEmail.setText(lstStudentID[e.parameter.lbxStudentInfo][8]);// sets Email
// txtExt.setText(lstStudentID[e.parameter.lbxStudentInfo][1]);// sets Ext
return app;
}