Sum varying length blocks of data

Hi,
I need some help regarding the excel file attached herein. In the attached sheet as it is displaying the sum (in yellow color) of all the data sets or bunches in corresponding rows. I want that it would also display the same SUM in column F for each set as it is displayed in green color.... any help will be highly appreciated, i need it as soon as possible..........

see its working fine if we dont have any blank line or lines among data sets. But in case if it encounters some blank among data sets, then it stops working and produce wrong results. U can check by inserting one or two blank lines among data sets......