Multiple Problems!!

[Oqt1]

 

Im currently building a large vessel to venture around the solar system.. 

I pre build in the hanger.

Then delete all part exept the thing I wanna orbit.!

I'm trying to send the first part. BUT

 

I can't delete this part. It's the same as the one i the opposite side.. that deletes fine.. AND I tried reloading the vessel and delete this part first.. it deletes fine but the other one then wont!!!! (the entire part that are partially marked with red)

The trash sound comes.. but it's still there.. and at some point I couldn't even deselect it..

Second problem..

after attaching the part I wanna orbit to my rocket it says this..

 

I have the base game from steam... 2 weeks old... no dlc's.. no mods..!

I'm looking at a maybe 2100 part vessel here.. would be quite a hassel to rebuild it. If I can't reuse som prebuild parts!!

Edited September 29, 2019 by Oqt1

[TheDu]

i think your problem is with the root part.  that is usually a probe core or capsule, its the one part that essentially is the core of the ship.  if you delete the root part, you cannot do anything else until you place a new root part.  simply place a capsule, then you have full control back.  after you place the capsule, use the re-root tool to make one of the parts in the module you want to launch the root part.  then delete the dummy capsule and you should be back in business. 

this is a key part of making subassemblies, look into that feature.  it will help with your construction style as you can simply take off different modules and drop them in the subassembly menu.  then when you want to launch that module, pull it out of the subassembly menu and add on your ascent stage.