Populate a column with part of another

Hello,

this is my first time trying something more complex with SharePoint. I need to populate a column with parts of a name from an uploaded file. 
The file name is separated by underscores, which should make it quite easy. I'd tried to cobble together a formula which cuts the string between the 1st and 2nd underscore and populate another column with that value. 
I've tried this: =MID([Name],SEARCH("_", [Name])+1,SEARCH("_", [Name],SEARCH("_", [Name])+1)-SEARCH("_", [Name])-1)

Where "Name" is the name of the column where the file name, which I try to cut apart is located. 
My request seems unusual, and I haven't found anything similar on the net I could base my work on. 

SharePoint just gives me an error message, but no specifics. 

Best,
Andrés