estrusione con t-splines

[dany996]

Hello everyone, I am following a simple course in the use of tspline plugin for rhino5, but I am faced with an anomaly that I cannot solve. in carrying out the realization of a hammer, after the execution of the extrusion command I find myself with a form that is difformed by what I should get; In summary, the surface edges do not have any curvature despite the smooth display option being activated. I attach an image of what is produced by my extrusion and how it should be the final result.
thanks to anyone who wants to enlighten me.

 

[dany996]

I add, after several tests I discovered that the extrusion takes place correctly only if you select the various faces one at a time, the selection of all the surfaces in block (area delimited with the mouse) produces that result! Is it normal?

 

[enri]

select only those in front of the center not those on the sides.