Error validating Token

I have this class called ValidateToken, but I can not find the error because in the compilation everything is fine but when executing (in debug mode) the class sends me a message

  

Invalid syntax on line 1.

public bool validateToken(string TokenString)
{
    bool result = false;

    try
    {
        SecurityToken securityToken = new JwtSecurityToken(TokenString);
        JwtSecurityTokenHandler securityTokenHandler = new JwtSecurityTokenHandler();
        RSACryptoServiceProvider publicAndPrivate = new RSACryptoServiceProvider();

        if (securityKey.ToString() == null)
            return result;

        publicAndPrivate.FromXmlString(securityKey.ToString());

        TokenValidationParameters validationParameters = new TokenValidationParameters()
        {
            IssuerSigningKey = new RsaSecurityKey(publicAndPrivate)
        };

        ClaimsPrincipal claimsPrincipal = securityTokenHandler.ValidateToken(TokenString, validationParameters, out securityToken);

        result = true;
    }
    catch (Exception e)
    {
        result = false;
    }
    return result;
}

  

TokenString is the token I send from the client to validate with the server

Any questions in the code will be attentive. Greetings in advance.