Unable to show the invoice components to the manager in my app

I am learning Bonita so bear with me if my question is too simple.

I am creating an invoice review app. The overall flow is as follows: the employee fills an invoice and sends it to his/her manager and then the manager may approve or reject this request.

My business data model is:
InvoiceReportLine:
Name Type Multiple Mandatory
'label' STRING No No
'price' FLOAT No No

InvoiceReport:
Name Type Multiple Mandatory
'summary' STRING No No
'lines' FLOAT Yes #
'isApproved' BOOL No No
'comments' STRING No No

I have a business variable named 'report' which is an instance of 'InvoiceReport' class and the contract variable is called 'reportContract' instantiated from an omitted version('isApproved' and 'comments' are removed and are assigned as contract entries for the review task) of 'InvoiceReport'.

In the review form I want to show the details of the invoice and let the manager either approve or reject this request. The 'summary' is shown in a read only text-area widget and the 'lines' in a table.

Now the problem I face is that the value of 'summary' is shown in the review form but the values of the 'lines' is not shown and the table is empty.