The solution you posted,
[tex]z = \frac{2}{1 + i}[/tex]
is not simplified. You know that you can multiply top and bottom by the conjugate, right? Even so, you still won't get the right answer.
EDIT: I think I found it. From the 2nd to 3rd line, on the RHS you have
[tex](2iz + 1)(1 - i) = 2iz - 2iz + 1 -i[/tex]
, which is wrong. It should be
[tex](2iz + 1)(1 - i) = 2iz - 2i^2 z + 1 - i[/tex]
.