How can I merge these two surfaces?

I´ve been trying to follow the tutorials below to merge the two surfaces but I can´t perform a complete surface by joining them using "merge command" on IMA module.
https://www.youtube.com/watch?v=fNxURyMG0Yc
https://www.youtube.com/watch?v=P9FgEwXYBa8
The CATIA Version I´m using it is V5R21