MS SQL server in docker compose is not connecting

My docker compose file is the following. I have set the sa Password to ProductCatalogApi(!) as i try to docker-compose build it is successful. i try to run (attach the) the database container only to check if it works. docker-compose up mssqlserver. it is giving me the following error. which says cannot login to this db. Connection to catalogDB failed.
[S0001][4060] Cannot open database "catalogDB" requested by the login. The login failed. ClientConnectionId:34c70da8-1879-4c09-afad-333dac35bc62
.

version: "3.2"

networks:
 frontend:
 backend:

services:
 catalog:
  build:
     context: ./src/Services/ProductCatalogApi
     dockerfile: Dockerfile
  environment:
     - DatabaseServer=mssqlserver
     - DatabaseName=CatalogDb
     - DatabaseUser=sa
     - DatabasePassword=ProductApi(!)
  container_name: catalogapi
  ports:
     - "5000:80"
  networks:
     - backend
     - frontend
  depends_on:
     - mssqlserver

 mssqlserver:
  image: "microsoft/mssql-server-linux:latest"
  ports:
     - "1433:1433"

  container_name: mssqlcontainer
  environment:
     - ACCEPT_EULA=Y
     - MSSQL_PID=Express
     - SA_PASSWORD=ProductApi(!)
  networks:
     - backend

Source: StackOverflow