Accessed none from node/import in scene with blueprint

Hi everyone.
I have two questions.

First, is an error that i don’t understand.
When the variable dissolve in my cube blueprint attains 0.2 (first picture), then my variable ressolve in my sphere blueprint is decremented (second picture)…
Concretely it works (i think) but i have this error (last picture) when i stop “Play” … Maybe i don’t call correctly my variable “dissolve” in sphere blueprint ?

And second question is, if someone knows a command to import an object in the scene with the blueprint.
It’s the same thing. When my variable dissolve attains 0.2, i would like that my sphere appears in a same location of my cube.

Sorry for my english, i hope is understandable.
And sorry if is simply, i’m beginner in unreal et i’m very bad in programming …
Thank for your help.

You do not have the executions connected on your cast to cube, so it is never happening.

Sorry, it’s not the good picture for my sphere blueprint. This is the good.

I have found that sometimes the way you have it set up does not work. Try doing a cast and pulling the value from that. The error you get is because it can not find the variable you are trying to access.

Cast like that ?
Do you know what i must choose for object ?

Ok it’s not solve at all …

I resolve my question to spawn an object … but i realize my problem for variable is not solve …

Cubeblueprint is not assigned in the space automatically

I can’t assign it because it’s not appear in the window

However in my variable, i think it’s correctly assign

I read that i must to use the cast… but i’m not sure it’s like that ? (but it doesn’t work …)

Someone to tell me what i do ? …