You should make sure you've connect the WAN port (the one with the "circle of dots" icon) of your Time Capsule to your MacBook Pro, and set your Time Capsule to be in "Create a Network" (wireless AP mode) and "Share a single IP address" (NAT and DHCP) mode.
That way your Time Capsule will get its IP address from the DHCP server that runs on your MacBook Pro when your MacBook Pro is in Internet Sharing mode.