Failing making surface from BlendSrf

Hi. I am trying to blend this two surfaces [please refer to the attachment]. I have been using the same procedure for all my model, but it is failing to connect the last two surfaces I need to blend.
The preview is not showing either. I can set everything what I want, but when I press the blend surface last action to have it done…nothing appears.

Hope you can help me, thanks.

I also uploaded the file
tubes.3dm (200.6 KB)

it works here, but you may have to reduce the radius or use option same height, it creates a self intersecting surface otherwise.

This is strange, but doesnt work in my Rhino.

no idea, maybe its because of the settings in the beginning,


it works here

but as announced you get a selfintersecting surface so click on option same height
if the resulting shape is ok for you, or reduce the radius.

blend.3dm (314.1 KB)

Thank you a lot Richard. You always save my a**