Server Starts then stops

[RogueZombieDog]

ok so, i am trying to create a server for me and my friends using a modpack i made, but when i try to load it when i run the forge server it runs but then just disappears and doesnt start up the server, the vanilla one works fine but the second i try the modded one it doesnt work, any tips?

[RogueZombieDog]

how? because it closes automatically and i cant do anything about it when it disappears (sorry noob to these things)

[RogueZombieDog]

what/where is the command line (sorry this may get annoying)

[RogueZombieDog]

all i do is run the forge 1.12.2 jar file thing like i did with the vanilla one then the server is supposed to work, unless im just dumb and have been doing it wrong but instead of creating anything it just dissapears and the exact same ish point (i could try looking what it says just before it disappears if you want?)