iDRAC 8: Invalid certificate is uploaded

Hello,

we would like to replace the idrac certificate by an own certificate signed by our pki.

So I create a private key:

openssl genrsa -des3 -out idrac-private.key 2048

and a csr

prompt = no
default_md = sha256
req_extensions = req_ext
distinguished_name = dn

[ dn ]
C = MyCountry
ST= MyState
L = MyCity
O = MyCompany
OU = MyDepartment
CN = idrac.mydomain.com

[ req_ext ]
subjectAltName = @alt_names

[ alt_names ]
DNS.1 = idrac.mydomain.com
IP.1 = 10.11.12.13

openssl req -new -config /etc/ssl/zertifikat.conf -key idrac-private.key -out idrac.csr 

Our PKI signed the certificate with SHA2.

Import key

racadm -r 10.11.12.13 -i sslkeyupload -t 1 -f C:\service\idrac-private.key
SSL key successfully uploaded to the RAC

Import certificate

racadm -r 10.11.12.13 -i sslcertupload -t 1 -f C:\service\idrac.crt
ERROR: An invalid certificate is uploaded

Whats the problem of the import and how can I import the Root-CA and the intermediate CAs?

BR

Christian