Repeating Formula Help (Excel 2016)

Need help so that I don't have to go in and re-type the error that is happening in each cell. I want the following repetition but when I try to repeat the cell formula it changes the formula.

It currently reads:
B2 & Sheet3!A13
B2 & Sheet3!A14
B2 & Sheet3!A15
..... and so on
when I use the repetition by dragging the slider down is creates the formula
B6 & Sheet3!A16
B6 & Sheet3!A17
..... and so on

Why does it change the B2 to B6 and how can I fix it so that i don't have to go through 100 cells and change the B6 to B2?

Thanks in advance!

Attached to this reply. The cells I am trying to fix are on Sheet 1 from A27 down. They are pulling information from Sheet 3 from A2 to A102.

Perfect thanks!!