Chartkick Stacked column help


I am trying to create a stacked column chart like this . But I am getting it like this. Can anyone help me so that I can achieve the desired one. My code now is:

def project_cost_breakdown

  # ....

  @column_chart_data = [


      name: "Budget & cost overrun",

      data: [['Budget & cost overrun', 100], ['Budget & cost overrun', 300]]



      name: "Total cost",

      data: [['Total cost', 300]]



  respond_to do |format|

    format.html { render "project_cost_breakdown" }



And in view I do it like:

= column_chart @column_chart_data, stacked: true, title: 'Total cost vs. Budget'

I am using lib.