  We investigated the bound state problem of the S wave charged $D_1 \bar{D}^*$
($D_1' \bar{D}^*$) system in a chiral quark model by solving the resonating
group method equation. Our preliminary study does not favor the molecular
assumption of $Z^+(4430)$. On the contrary, if $Z^+(4430)$ is really a
molecule, its partner with opposite $G$-parity should also exist and probably
may be found in the $\pi^+\eta_c(2S)$, $J/\psi \pi^+\pi^0$, or
$\psi'\pi^+\pi^0$ channel. For the bottom systems, we found the existence of
both $I^G$=$1^+$ and $I^G$=$1^-$ $B_1 \bar{B}^*$ ($B_1' \bar{B}^*$) molecules
is possible.
