How to decrypt the SOAP request

Question

Hi,My requirement is to apply WS Security using RSAwithSHA256 using a certificate.

This is how I am applying WSS to my XML:
Apply WSS.txt

After applying WSS, I send a SOAP request and receive an encrypted response whose body is like: encrpted response.txt

I am decrypting the response like this:
Decrpyt Response.txt

But I am getting an error "The parameter is incorrrect" at
byte[] decryptedKeyBytes = (await GetPrivateKeyFromPem()).Decrypt(encryptedKeyBytes, RSAEncryptionPadding.OaepSHA1);

Can you help me with how to decrypt the response?