Excel file name issue in send mail task using SSIS

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SSIS

I have a package which is creating a excel file 'ExcelName.xls' and storing in 'E:\Reporting\Delivered_Reports'. Now I have to attach this report using send mail task and send it to given mail id. To achieve this I have configured the send mail task and in Expression Builder, I have selected the below expression:

"E:\\Reporting\\Delivered_Reports\\ExcelName_"+
((DT_WSTR,4)Year(@[System::StartTime]))+
RIGHT("0"+((DT_WSTR,2)Month(@[System::StartTime])),2)+
RIGHT("0"+((DT_WSTR,2)Day(@[System::StartTime])),2)+".xls"

I need file name should be 'ExcelName_20150601' where suffix is the current date. But I recieve file which name is 'ExcelName', which is the origional file name. Can you tell me where I am wrong?

Thanks in advance