How to pass a vector or function to bvpinit?

my 2nd order ode and boundary conditions look like this:

f = @(x,u) [ u(2); someconstant*x*somefunction(u(1))];
g = @(ya,yb) [ya(1)-bcleft; yb(2)-yb(1)/someconstant2];

then I try the following:

r=linspace(0,someconstant,1000); 

y1guessvec=r.*someconstant;
y2guessvec=r.0;
y1guessfun=@(x) x.*someconstant;

neither

solinit=bvpinit(r,[y1guessvec y2guessvec]);

nor

solinit=bvpinit(r,[y1guessvec 0]);

nor

solinit=bvpinit(r,[y1guessvec y2guessvec]);

do work. Unfortunately, the manual is completely useless...there's not a single example besides using some constant [0 0] in bvpinit...

what am I doing wrong?