<xsl:variable name="result">
            <dp:url-open  ssl-proxy="client:Datapower_External" target="https://192.168.68.44:5006/oauth/v1/token" response="responsecode-binary" http-headers="$httpHeaders">
                <xsl:copy-of select="current()"/>
            </dp:url-open>
        </xsl:variable>

i use this code to make http call to a token service and then set the token in http header of the main request 
in ssl-proxy attribute i inserted the client profile including the token service certificate , but i only get error : url-open: Cannot create connection to 'https://192.168.68.44:5006/oauth/v1/token' ,

so what can be wrong with my code 

thank you in advance

Hi Fatma,
What do your transaction logs (default-log) indicate? Just looking at the code you provided, you must have a tls client profile named Datapower_External and you have setup your request headers to send to the target in a variable named httpHeaders which would need to be a nodeset configured like the example in the documentation

<xsl:variable name="httpHeaders">
  <header name="requestheader1">value1</header>
  <header name="requestheader2">value2</header>
</xsl:variable>

I'd suggest you enable debug logging and you should start reviewing the logs for your failing transaction starting with the network logs indicating that a connection is being attempted to https://192.168.68.44:5006/oauth/v1/token.  For a connection issue, I would expect the issue could be SSL related or perhaps a firewall not allowing the traffic to go through.  Another test would be to use a DataPower packet capture where you would filter using host 192.168.68.44 and also enable tls session keys which would capture all traffic between the appliance and your backend server.  The packet capture will be saved in your temporary directory and the tls session keys in your logtemp directory.  The tls session keys will allow you to decrypt your ssl traffic using a tool such as wireshark so you can see exactly what is being sent to your backend including the SSL Handshake and any server responses.  Odds are there is a RST packet coming into DataPower to close down the connection.  Hopefully between the logs and the packet capture you can figure out what is going on.

Best Regards,
Steve