Microsoft teams GraphAPI returning errors - microsoft-graph-api

Question

I am having an issue with hitting POST APIs(send message, create channel) from our Graph API app.
First request is for create channel:
Request URL: https://graph.microsoft.com/v1.0/teams/id/channels
Post Body:
{:displayName=>"new channel", :description=>"description"}
Headers also include the bearer token from the authorization API
Error received:
{:code=>"BadRequest", :message=>"channel cannot be null.\r\nParameter name: channel", :innerError=>{:date=>"2020-06-24T12:40:33", :"request-id"=>"be91ce7b-0"}}
Documentation that I followed: https://learn.microsoft.com/en-us/graph/api/channel-post?view=graph-rest-1.0&tabs=http
Second request is of send message to channel:
Request URL: https://graph.microsoft.com/v1.0/teams/bc71-8b158cc3b3/channels/19:ec73841#thread.skype/messages
Post Body:
{:body => {:contentType=>"html", :content=>"Tesing message from graph api"}}
Headers also include the bearer token from the authorization API
Error received:
{:code=>"InternalServerError", :message=>"Failed to execute request.", :innerError=>{:date=>"2020-06-24T12:42:01", :"request-id"=>"ed601c89-f0bd3"}}
Documentation that I followed: https://learn.microsoft.com/en-us/graph/api/channel-post-messages?view=graph-rest-1.0&tabs=http