Loop without Do error

I'm trying to implement a simple Newton's method iterative solver using Excel VB (I have never used VB.) I keep getting the error `loop without a Do` and I can't figure out what I'm doing wrong here. I'm trying to find the roots of the function `z^3 - z^2 - (B^2 + B - A)z - A*B` called the compressibility factor. My source MSN ``` Function zCalculation(ByVal temp As Double, ByVal press As Double) As Double Dim tempCr As Double Dim pressCr As Double Dim A As Double Dim B As Double tempCr = temp / 238.5 pressCr = press / 547.424092 A = pressCr / tempCr A = A / (9 * (2 ^ (1 / 3) - 1)) B = pressCr / tempCr B = B * (2 ^ (1 / 3) - 1) / 3 Dim zNot As Double Dim counter As Integer counter = 0 zNot = 1# Do counter = counter + 1 zNot = zNot - (zNot ^ 3 - zNot ^ 2 - (B ^ 2 + B - A) * zNot - A * B) / (3 * zNot ^ 2 - 2 * zNot - (B ^ 2 + B - A)) If counter > 1000 Then Exit Do Loop Until eval(zNot, A, B) < 0.000001 zCalculation = zNot End Function ``` break ``` Function eval(ByVal z As Double, ByVal A As Double, ByVal B As Double) As Double eval = z ^ 3 - z ^ 2 - (B ^ 2 + B - A) * z - A * B End Function ```