Adding refrenced cells in Excel 2013

So I have been trying to add refrenced cells but each time I input the sum formula is get 0 as an answer. I did a search online and realised that I'm to use the indirect formula but I just caot make head or tail of it. At best I am able to retrieve one number but my intention is not retrieval alone but adding the numbers in the refrenced cells. Any help will be greatly appreciated

Oops I caot post pictures at the moment but I hope the description of my headache will be understood from the three points below:

1. In I2, sum A2:D2
2. In J2, sum lowest 2 numbers in E2:H2
3. In K2, sum I2 and J2

Please note that the values in A2 to H2 are referenced from another sheet.

Thanks in advance.