does anyone use wildcard certificates?

i am unable to create a csr with common name *.mydomain.com
Error Message:
"The Common Name specified is invalid".

Zenworks 2017 Server on SLES12 SP2
ZCM : 17.0.0.0
ZAM : 17.0.0.1187
ZPM : 17.0.0.737
ZESM : 17.0.0.1187
ZFDE : 17.0.0.1187


regards
Andreas