I had came across a rather stupid problem. I had an Excel chart which has some data and a nice graph on a Word document. the problem was, when I wanted to edit the data and change the graph, the chart did not get updated. The data and chart is updated on the excel sheet, but no on word.
How to solve this problem:
1. Highlight the graph
2. Under the top tab, go to Chart tool.
3. Under the Data group, click Refresh Data.
Hope this helps somebody.