I've created a GUI (`MyGui`) with a flow panel (`mainPanel`), a text box (`textValue`) and a button (`getETA`). All in a sites script.

The idea is that a value is entered in the text box, the button is clicked and the value is then placed in the cell A1 of a spreadsheet.

There is no handler configured in the GUI and I've copy pasted the script to a fresh site, no success though.

The problem I'm having is that all I get in the spreadsheet cell is "undefined".
Also if I run a debug on the `clickGetETA` function I get the following error message: "Cannot read property "parameter" from undefined"

I'm new to this but my best guess is that the details of the GUI are not being passed on to the `clickGetETA` function. I've searched what I can but I can't appear to find a solution...

If someone could tell me where I'm going wrong I'd appreciate he help.

```
function doGet() {
    var app= UiApp.createApplication();
    app.add(app.loadComponent("MyGui"));
    var clickHandler = app.createServerHandler('clickGetETA');
    clickHandler.addCallbackElement(app.getElementById('mainPanel'));
    app.getElementById('getETA').addClickHandler(clickHandler);
    return app;
}

function clickGetETA(e) {
    var sheet = SpreadsheetApp.openById('abcdefghjklmnopqrstuvwxyz');
    var ss = sheet.getActiveSheet();
    var target = ss.setActiveCell("A1");
    target.setValue(e.parameter.textValue);
}

```