Cannot Connect Kubernetes Secrets to Kubernetes Deployment (Values Are Empty) - kubernetes

Question

I have a Golang Microservice Application which has following Kubernetes Manifest Configuration...
apiVersion: v1 # Service for accessing store application (this) from Ingress...
kind: Service
metadata:
name: store-internal-service
namespace: store-namespace
spec:
type: ClusterIP
selector:
app: store-internal-service
ports:
- name: http
port: 8000
targetPort: 8000
---
apiVersion: apps/v1
kind: Deployment
metadata:
name: store-application-service
namespace: store-namespace
labels:
app: store-application-service
spec:
selector:
matchLabels:
app: store-internal-service
template:
metadata:
labels:
app: store-internal-service
spec:
containers:
- name: store-application
image: <image>
envFrom:
- secretRef:
name: project-secret-store
ports:
- containerPort: 8000
protocol: TCP
imagePullPolicy: Always
env:
- name: APPLICATION_PORT
value: "8000"
- name: APPLICATION_HOST
value: "localhost"
terminationGracePeriodSeconds: 60
---
apiVersion: v1
kind: Secret
metadata:
name: project-secret-store
namespace: store-namespace
type: Opaque
stringData:
# Prometheus Server Credentials...
PROMETHEUS_HOST: "prometheus-internal-service"
PROMETHEUS_PORT: "9090"
# POSTGRESQL CONFIGURATION.
DATABASE_HOST: "postgres-internal-service"
DATABASE_PORT: "5432"
DATABASE_USER: "postgres_user"
DATABASE_PASSWORD: "postgres_password"
DATABASE_NAME: "store_db"
And Also for Test Purposes, I've specified following Variables in order to receive values from secrets in my application..
var (
POSTGRES_USER = os.Getenv("DATABASE_USER")
POSTGRES_PASSWORD = os.Getenv("DATABASE_PASSWORD")
POSTGRES_DATABASE = os.Getenv("DATABASE_NAME")
POSTGRES_HOST = os.Getenv("DATABASE_HOST")
POSTGRES_PORT = os.Getenv("DATABASE_PORT")
)
The Problem is when run my application, and after some time go check the logs of my application using kubectl logs <my-application-pod-name> --namespace=store-namespace, turns out that all this Golang variables are empty, despite the fact that they all has been declared in the Secret...
There is probably some other issues, that can cause this problem, but if there is some errors in configuration to point out, please share with your thoughts about it :)