Table of contents not displaying custom text in field

[wrdy]

In the body of my document, the chapter headings are simply numbered 1,2,3..., but in the table of contents I want to add the word "chapter" like this:

Table of Contents
Chapter 1
Chapter 2


Chapter 3
...

I've used Shift+Alt+O to "Mark Table of Contents Entry" resulting in:

1{ TC "Chapter 1" \f C \1 "1"}

I update the table of contents, but it still shows:

Table of Contents
1
2
3

What could be the problem?

MS Office 2010