Macro - copy and paste cells from one to another

Hey,

I have created a macro which takes a list from sheet 1 and copies to sheet 2.

Once in sheet 2 i am doing the following in column c (=sum(a1+b1)), i am doing this for however many items were copied from sheet 1 to 2.

The problem occurs when i add more information into sheet 1. Once the macro runs it copies everything from sheet 1 to 2 and adds the cells a1+b1 all the way down to a100+b100 (copied 100 items over). Once i try to copy more than 100 items (200 for example) my Macro doesnt automatically add these and include them in sheet 2. It copies all of the information over but the =sum(a1+b1) only seems to be working down to a100+b100.

Any ideas please?

Thanks