Selection Rules

An operator $W=lambdavec{S}cdotvec{r}$ is given, and I’ve to find his selection rules.
First of all, I know that $Delta j = 0$ and $Delta m_j=0$ because the operator commutes with the total angular momentum.

But, I’m not sure about $Delta l$, I know that the answer will be $Delta l =pm1$, but I don’t see why. I tried to calculate the matrix elements using pairty, and I got:
$$<j’,l’,s;m_j’|lambdavec{S}cdotvec{r}|j,l,s;m_j>=<j’,l’,s;m_j’|Pi^{dagger}Pilambdavec{S} Pi^{dagger}Pivec{r}Pi^{dagger}Pi|j,l,s;m_j>$$

$$=-(-1)^{l+l’}<j’,l’,s;m_j’|lambdavec{S}cdotvec{r}|j,l,s;m_j>$$.

But I don’t know how to solve it from here.