strange problem in CST

Hi there
i design a structure in CST and simulated it successfully. the structure has 4 port. then rotated the structure by 180 degree and re assigned the ports.
now when ever i change a parameter named "extra" port 3 get deleted from structure.
i want to start a parameter sweep but could not do because one port, port 3 get deleted as soon as i change parameter " extra"

i have attached the design
it would be a great help if any one could check the design once and point out my mistake or its cause

the structure in design in CST 5.

thanks

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