Click Ctrl and Drag and Drop the Reading measure on the Column shelf. Change the chart to Bars using the Marks section drop down above color and size Marks. Then dual axis it. You will be able to see the lines and bars together.
Thanks for your reply. But the thing is if i'll do it this way then the filter gets applied on both the graphs i.e. zipcode and customerID gets applied on bar chart and line chart both. What I want is Zipcode filter to be applied only on line chart and customerID to be applied only on bar chart