nodeTimeMatrix(i,i2) is a scalar, assuming i and i2 are scalars then this just indexes into a single location of a 2d matrix. I would guess that adjustment is in fact a 1-by-10000.
This can be checked easily simply by debugging and looking in the workspace in a breakpoint there.
nodeTimeMatrix(i,:) = nodeTimeMatrix(i,:) + adjustment;
may be what you want, at a guess.