appearing grey in preview,

[Adamsk1 0]

could i have some help with a print, I'm kind confused why this is happening,(ender3 v2 btw)(cura 5.4.0) my print when scaling up doesn't work and instead appears grey 

[ahoeben 1,968]

Your model appears to be broken. At the very least the normals of some of the faces are flipped. You might be able to repair the normals in Cura with the Mesh Tools plugin from the Marketplace, or you can load the model into 3d Builder (comes with Windows) and let it repair the model when it tells you that "One or more models are invalidly defined", then save it as a new STL.