SSL Keystore not initialized when it contains only CA certs (no private keys).

I am using SOAPUI 5.6.0. and have created a keystore with a certificate in it.

I have attached keystore to the Project with a password and it and this is ok (Green Tick)

When I try to run my Request with the certificate I get the  following error

Thu Jul 23 20:00:57 AEST 2020:ERROR:java.security.KeyStoreException: Uninitialized keystore

java.security.KeyStoreException: Uninitialized keystore

at java.base/java.security.KeyStore.aliases(KeyStore.java:1260)

at java.base/sun.security.ssl.SunX509KeyManagerImpl.<init>(SunX509KeyManagerImpl.java:139)

Any suggestions / help would be appreciated.

Thank You