Can anyone help with this?

I want to do a port monitor on my Cisco 2950 to troubleshoot some SIP in dial issues. I have set this up successfully before on the Samsung GPLIM cards using the GUI. However when I do this on my 2950 my computer won’t connect through the monitor destination port.

After setting up the span ports and type show monitor at the enable prompt I get this which I think should be correct.

Source Ports:
RX Only: None
TX Only: None
Both: Fa0/23
Destination Ports: Fa0/24

My Intention is to connect laptop with wire shark to 24 and MCP to 23.

As soon as I type no monitor session 1 the laptop connects through port 24 again. And I can see things happening on wireshark again.