Display methods on SSRS report AX7

Hi,

I need to know how can we use display methods in SSRS reports. I am having an issue. I have created extension class for an existing table. and under that class I have written my display method. 

[SysClientCacheDataMethodAttribute(true)]
public display CustAccount CustAccount(ProdTable _prodTable)
{
    CustAccount custAccount;

    if (_prodTable.InventRefType == InventRefType::Sales)
    {
        custAccount = SalesTable::find(_prodTable.InventRefId).CustAccount;
    }

    return CustAccount;
}

My report is a query based report. 

I am able to see the display method in report and also I have dropped the field into the report design. But there is no value on the report.

Please guide me though this.