I tried to solve the inequality
$$ b^2 c^2 - 4 c^3 - 27 d - 4 b^3 d + 18 b c d > 0$$
using
FindInstance[b^2 c^2 - 4 c^3 - 27 d - 4 b^3 d + 18 b c d > 0, Reals]
but I get the error
"The system contains a nonconstant expression b independent of \
variables {\!\(\*TemplateBox[{},\"Reals\"]\)}."
Any idea why, or alternative method to solve the inequality?