Understanding Strings

Let's say that I'm checking an opcode (like 267) that have as a parameter a string.

Where can I see what text this string is related to?

I tried to check the Dialogue.tlk using Notepad, but I'm having no success - maybe I'm doing something wrong.

Let's say that the opcode 267 is related to string 26018. I open the dialogue .tlk and search for the row #26018, but the text that displays there doesn't make sense for the opcode propose (in this case, the monk's disease immunity).

Thanks!