unresolved typeref token (0100001B) for '_masterListT'; image may not run

I have the following link error in the C++\CLI library that uses the latest FDK libraries.

Where exactly is the problem?

Inside the f_types.h file there is (in line 239):

/* string list */

typedef struct _masterListT *StringListT;

What is the problem?

This is a link warning, but I would like to resolve it.

Thank you.