When a research committee has approved your proposal, the next step is a literature review. A literature review can be developed in two steps:

1. A critical evaluation of existing research papers, scholarly articles/journal articles, white papers, government records or any other theory in relation to the research problem that you choose for further investigation. This step mainly involved identifying the research gap.  
2. Refining, segregating and comparing the literature as per your research objectives.

A basic laying out of two seemingly-simple steps mentioned above itself seems a daunting task. It is obvious that it is easier said than done, and some ‘errors’ are bound to be committed by you while writing a literature review chapter for your PhD thesis.

Your Writing Lacks Synthesis
When you write a literature review, the first thing you have to bear in mind is synthesising of all information that you have drawn from reviewing papers.  You have to consolidate what matter was clear in previous studies, what part was obscure, and what parts were missing altogether so that readers can decipher your message explicitly.

For instance, if your topic for a literature review is ways to whittle down the rate of cybercrime, you have to mention recent citations that will be relevant to your research topic. It should include, for example, increasing rate of cybercrime over time, law enforcement, existing tools to detect crime, challenges faced by cybercrime investigation authorities etc. You would then bring one of the obscure areas into attention that would justify your research objectives.

You haven’t Critiqued the Research Adequately
A literature review does not mean consolidating what is currently known about a topic but to justify for your research work by finding limitations in earlier studies. A coherent and comprehensive critique of the literature reviewed is the key. You have to identify the limitations and drawbacks of previous research attempts and convince the committee why it’s necessary to fill research gap.

For instance, in the aforementioned topic, what preventive measures were not considered to diminish cybercrime rate in old literature, and what technological drawbacks became an impediment to improve the situation but were not identified until then. By addressing these loopholes, you can justify how addressing these issues are vital to meet objectives.

You Used Irrelevant Material
A literature review does not demonstrate what you have read; it instead reveals how a certain part of the material that you have read provides the basis for your research. For instance, in the above mentioned topic, you will include citations that somehow relates to cybercrime. If you add anything that surrounds crime but not cybercrime, your literature review will digress, and you will not be able to justify it to your research committee. In addition, it is suggested to use only the most recent (and updated) resources for literature reviewing.

Summing Up
The bottom line is to write an accurate literature review for your thesis, you should know about your research objectives and how your work is going to meet them. If you face difficulty finding relevance in previous studies that could serve the purpose of your research, don’t hesitate to consult your supervisor to catch hold of a perspective for critiquing literature to suit your research.