Generalized Euler-Lagrange (m,n)-cubic functional equation and its stability

In this article, we introduce a new generalized Euler-Lagrange $(m,n)$-cubic functional equation with its general solution. Also, we investigate its various stabilities related to the Ulam problem in fuzzy normed linear spaces using Felbin's concept. Also, we provide a counter-example for the non-existence of stability of a generalized Euler-Lagrange $(m,n)$-cubic functional equation.