SSL traffic is not being decrypted despite having a correctly defined key.
The following method verifies if you have the proper private key using OpenSSL:
a) Get the certificate from the wire
Make sure the traffic is decoded as SSL, i.e. setup the SSL analyzer for this TCP stream in Analyze >> Decode As. Now it will show the SSL details for the packets.
Pick the packet which contains the certificate, in this case packet 6.
In the packet details expand Secure Socket Layer etc until you get to the certificate itself:
Use the context menu (right click) and save the raw data of the certificate with Export Packet Bytes into a file, for example cert.der.
With openssl x509 -inform der -in cert.der -text you can have a look at the certificate, with openssl x509 -inform der -in cert.der -outform pem -out cert.crt you can convert it into a PEM format (i.e. what you mean with crt format).