Subscripts in Emacs 24.4.1 not showing up properly - emacs

Question

I'm working on an assignment that used the unicode subscript k ("\_k"). However, instead of getting the subscripted k, I get this:
![][1]
The can still use subscripts with numbers and some letters, but not with 'k'.
I initially had the issue with emacs 24.3, and then was told to update to 24.4. The issue still persisted.
Has anyone else had this issue and found a solution?
I'm running on a Mac with Emacs v.24.4.1
Thanks in advance
EDIT
Here is my .emacs file:
(load-file (let ((coding-system-for-read 'utf-8))
(shell-command-to-string "agda-mode locate")))
(set-default-font "-apple-DejaVu_Sans-medium-normal-normal-*-*-*-*-*-p-0-iso10646-1")
; Change Control-c Control-, and Control-c Control-. in Agda mode
; so they show the normalized rather than the "simplified" goals
(defun agda2-normalized-goal-and-context ()
(interactive)
(agda2-goal-and-context '(3)))
(defun agda2-normalized-goal-and-context-and-inferred ()
(interactive)
(agda2-goal-and-context-and-inferred '(3)))
(eval-after-load "agda2-mode"
'(progn
(define-key agda2-mode-map (kbd "C-c C-,")
'agda2-normalized-goal-and-context)
(define-key agda2-mode-map (kbd "C-c C-.")
'agda2-normalized-goal-and-context-and-inferred)))
; This defines backslash commands for some extra symbols.
(eval-after-load "quail/latin-ltx"
'(mapc (lambda (pair)
(quail-defrule (car pair) (cadr pair) "TeX"))
'( ("\\bb" "𝔹") ("\\bl" "𝕃") ("\\bs" "𝕊")
("\\bt" "𝕋") ("\\bv" "𝕍") ("\\cv" "⋎")
("\\comp" "∘") ("\\m" "↦") ("\\om" "ω"))))
; This sets the Control-c Control-k shortcut to
; describe the character under your cursor.
(global-set-key "\C-c\C-k" 'describe-char)
(custom-set-variables
'(agda2-include-dirs
(quote ("." "/Users/dylanthiemann/Dropbox/University of Iowa/2nd Senior Year/Spring 2015/PLC/ial")))
)
And the bit of code is from Agda:
module bool-kleene-thms where
open import bool
open import bool-kleene
open import eq
&&ₖ-idem : ∀ (b : 𝔹ₖ) → b &&ₖ b ≡ b
&&ₖ-idem b = {!!}
tt-&&ₖ : ∀ (b : 𝔹ₖ) → tt &&ₖ b ≡ b
tt-&&ₖ b = {!!}
||ₖ-idem : ∀ (b : 𝔹ₖ) → b ||ₖ b ≡ b
||ₖ-idem b = {!!}
||ₖ-tt : ∀ (b : 𝔹ₖ) → b ||ₖ tt ≡ tt
||ₖ-tt b = {!!}
||ₖ-ff : ∀ (b : 𝔹ₖ) → b ||ₖ ff ≡ b
||ₖ-ff b = {!!}
Edit 2
Results of Ctrl-u Ctrl-x = on affected character:
position: 91 of 830 (11%), column: 2
character: ₖ (displayed as ₖ) (codepoint 8342, #o20226, #x2096)
preferred charset: unicode (Unicode (ISO10646))
code point in charset: 0x2096
script: symbol
syntax: w which means: word
category: .:Base, L:Left-to-right (strong)
to input: type "\_k" with Agda input method
buffer code: #xE2 #x82 #x96
file code: #xE2 #x82 #x96 (encoded by coding system utf-8-unix)
display: terminal code #xE2 #x82 #x96

Answer 1

I needed to install new fonts... I used this http://dejavu-fonts.org/wiki/Download and then installed using Font Books. The issue was then resolved!