Rocket Lab Corp (NASDAQ:RKLB) shares are down on Monday as investors weigh mixed news from a successful recent launch and an issue during testing of its upcoming Neutron rocket. Here’s what investors need to know.Rocket Lab shares are sliding. What’s weighing on RKLB shares?Rocket Lab Balances Successful Electron Launch With Neutron Testing SetbackRocket Lab's latest Electron mission, "The Cosmos Will See You Now," last week successfully delivered two satellites to orbit for European space tech firm Open Co ...