Hello
I am Prakash and I will be glad to assist you today with your question.
I will suggests that the open document contains text formatted in a language whose proofing tools you haven't installed or that no proofing tools have been installed for your default proofing language.
You can download Office 2013 proofing tools from https://www.microsoft.com/en-US/download/details.aspx?id=35400. Pick the appropriate language in the drop down list.
I hope this information helps to answer your question. Kindly let me know how it goes and do not hesitate to reach out to me for any additional help.
Thank you
Prakash