Going from the error, it seems that you are trying to use mesh for a 1D array (Z in your case). Mesh expects the 'Z' to be a 2D matrix containing all the values of the function, i.e. Z = f(x,y) as in the example from http://www.mathworks.com/help/matlab/ref/mesh.html :
figure;
[X,Y] = meshgrid(-8:.5:8);
R = sqrt(X.^2 + Y.^2) + eps;
Z = sin(R)./R;
mesh(Z);
So from http://www.mathworks.com/help/matlab/ref/plot3.html : plot3(X1,Y1,Z1,...), where X1, Y1, Z1 are vectors or matrices, plots one or more lines in three-dimensional space through the points whose coordinates are the elements of X1, Y1, and Z1.
whereas from http://www.mathworks.com/help/matlab/ref/mesh.html : mesh(X,Y,Z) draws a wireframe mesh with color determined by Z, so color is proportional to surface height. If X and Y are vectors, length(X) = n and length(Y) = m, where [m,n] = size(Z).
You got to make sure that size(Z) is [m,n]!
