How to Use CheckBox or To calculate value using Checkbox

Hi all, I am new to mendix and i do not know how to use checkbox within dataview.  Basic Details is I am Creating Travel Insurance application in that i need to create three Categories Like normal, Premium and Luxury.  I have created table like structure with 3 Columns as Normal, premium and Luxury. In that columns premium and Luxury I have to place checkbox for covering personal objects like Passport, Medical etc and the condition for checkbox is " If the user selected the checkbox certain percentage(say like 10%,20%) of main fee will be added to result ..  and Microflow procedure for Checkbox activity Please tell me or Advice me to do this in Step by step manner with an Example, so that i do Easily.. Thanks in Advance     I try to use On-Enter Events and On-Leave Events in checkbox properties to add their values(Certain Percent% from main fee to result) But am getting Error as "Error Occurred while handling the request.. I have added screenshot for ur reference
1 answers

As Erwin suggests, you should be using an on-change microflow. If you look in the console tab in your modeler, you'll see the error that is occurring. Usually this is caused by an empty reference being used in the microflow. You could also using the microflow debugger to set a breakpoint and keep track of your variables values in each step of your microflow. If you can't interpret the error message, please share the full contents with us in an edit to your question.