Using the openssl passwd in useradd -p openssl passwd "1234" on NIS server

1. To get the crypted password with openssl passwd '1234'
2. useradd -p "above results" test1
3. Update the NIS databse
4. su - test1 on NIS server, enter the password:1234; then showing incorrect password
5. Also try passwd test1, then try to su - test1, it also shows incorrect password
6. su - test1 on NIS Client is ok

Dose anyone know what's the problem? Thanks~