Dealing with a weird problem while using Excel 2013 for a machine learning project .(RRL using GRG Solver)

what i want in column C is the difference of Today's Asset Price & Yesterday's.

(Eg:C2= $B2-$B3, C3=$B3-$B4, and so on)

I put ' =B2-B3' in Cell C2. Then pressed an Enter and got the result as 38.18.

Then I dragged The column C2 downwards, (to fill the successive columns according to the formula).What happened was the 38.18 is repeating in all other C cells.

Suggest Me Fix.