Excel problems with copying a formula

My excel is behaving funny. When I copy a cell formula across the row or column, it copies the formula correctly, but does not give the corresponding value!!

Example: If Cell B1 has the value 20. Suppose I type =B1+1 inside cell B2, that gives me 21. Now, when i use Ctrl+C to copy cell B2 to cell B3, I should get the value 22. Instead, it still reads 21. However, the formula inside the cell correctly reads =B2+1. Its bizarre.

Autofill gives me the same problem. BUT, if i manually type in the formula into cell B3, it gives me the correct value 22. And that defeats the purpose of Excel, because I cannot manually type a formula into every single cell!!!!

Please HELP!