Hi,
This means that you are missing the reference to the static library (should be called libPoco.a or something similar). Note that if you have just downloaded the sources from Internet, you need to configure and build the library according to the instructions provided by its vendor. This will produce the .a file that you can reference from VisualGDB Project Properties (normally add the directory with the .a files to the Library Directories and add the library name without the ‘lib’ prefix to the Additional Libraries).