Hello.
Were these custom fields added into form definition of the given document in a standard way, in the Site Manager / Development / Document types / edit / Fields tab?
If you call macro below in some web part's property placed on that page, does it return required value?
{%CurrentDocument["<column code name>"]%}
Where exactly you call that
CMSContent.CurrentDocument.GetValue("someFieldName") code? As this is not a macro expression but direct C# code, I guess you call it somewhere in the code-behind?
When you debug it, it "CurrentDocument" object not null and are you sure that codeName in GetValue() method is correct? Thank you.
Best Regards,
Radek Macalik