Please help to Find the last 6 Months Total Qty from Monthly Data (SUMPRODUCT FUNCTION)

Kindly help me, please.

I am looking for the last Six Month Total Qty , from DataBase sheet , by looking up "Month Date + Item Code".

Eg. If current month is July 2015 , Sum Total qty for Jan to June 2015 (the last 6 Months) .
If next month is August, want to get data automatically of Feb to July .

I am trying to use with Sumproduct . But, I can't get the correct data . Help me to correct the formula, please , or kindly give me the right formula.

TEST FORMULA:

1) SUMPRODUCT((ROUNDUP(MONTH(DATABASE!$C$2:$C$15000)/6,0=1)*(DATABASE!$A$2:$A$15000=B27)*(DATABASE!$E$2:$E$15000))))


2) SUMPRODUCT((DATABASE!$A$2:$A$15000=B27)*(MOD(--MONTH(DATABASE!$C$2:$C$15000)/6,0))*(DATABASE!$E$2:$E$15000))

3) SUMPRODUCT((DATABASE!$C$2:$C$15000=B4)*(SUMPRODUCT((DATABASE!$C$2:$C$15000>DATE(2015,1,1)),(DATABASE!$C$2:$C$15000<DATE(2015,6,30))*(DATABASE!$E$2:$E$15000))))



Here is attached of the excel sheet.
Thanks in advance !

See attached. I have added 2 fields in L2 & M2 for Start/End of 6 month period.

Thanks, John (JohnTopley). This is what I wanted. You helped me again ! Thanks a lot !

Thank you for your advise Oeldere. Appreciated for your effort and time.