Issue with 'Plan Requirement Coverage by Test Case' Report

'Plan Requirement Coverage by Test Case' Report is not coming properly.

I have created 1 Test Plan, 6 Requirements & 2 Testcases against 2 requirements. After that 'Test Plan' is associated with 'Requirements' & 2 'Test Cases' are associated with 2 'Requirements'. Under 'Edit Settings', Scope & Preferences are also selected. But still 'Pie Chart' Report for 'Plan Requirements Coverage by Test Case' is not coming properly.

It is showing 6 uncovered requirements.

Please Suggest me exact procedure for that.