?mxAlgebra example code doesn't run

Documentation helper gives an error
Running AlgebraExample
Error in mxRun(modelD) :
MxAlgebraObjective's objective algebra does not evaluate to a 1x1 matrix.

I'd suggest this:

A <- mxMatrix("Full", nrow = 3, ncol = 3, values=2, name = "A")

# Simple example: algebra B simply evaluates to the matrix A
B <- mxAlgebra(A, name = "B")

# Compute A + B
C <- mxAlgebra(A + B, name = "C")

# Compute sin(C)
D <- mxAlgebra(sin(C), name = "D")

# Make a model and evaluate the mxAlgebra object 'D'
A <- mxMatrix("Full", nrow = 3, ncol = 3, values=2, name = "A")
model <- mxModel("AlgebraExample", A, B, C, D )
fit <- mxRun(model)
mxEval(D, fit)