Implementing Linechart With Datasource Request

I'm completely new to api's.
I want to implement a Dashboard in WordPress using Google Visualization API.
I installed and activated the Google Visualization Chart plugin. I was using the LineChart API in the Google Code Playground, changed some data and produce a nice line chart. However, I want to collect the data I manually entered from a Google sheet.
How do I make a sheet on a Google Drive accessible to the API plugin?
I need to merge the code from the LineChart API with the Data Source Request API.
I have this code:

var data = response.getDataTable();
  new google.visualization.LineChart(document.getElementById('dashboard')).
      draw(data, {curveType: "function",
                  width: 500, height: 400,
                  vAxis: {maxValue: 10}}
          );

Code (markup):

and getting this error:
TypeError: google.visualization.LineChart is not a constructor.....
Can someone advise on what I'm doing wrong?
Grateful for any help with this.