Why doesn't the tlc function LibMdlStartCustomCode work in 2014b and later?

I have made my own blockset for generating c-code for STM32 microcontrollers. In one of the tlc files I use LibMdlStartCustomCode for adding a declaration in the model_initialize() in the model c-file. This function works fine in all Matlab versions from 2009b until 2014a. In 2014b and 2015b I noticed that this function no longer seems to work, although it is still present in the documentation.

When I build the same model in 2014a, 2014b and 2015b, I get no errors in 2014a and the declaration is added correctly but in 2014b and 2015b I get an error during the build procedure because the declaration is not added. This is an example of the code in the tlc file:

%%Declare a variable for storing the CAN filter configuration.
    %<LibMdlStartCustomCode("tCanFilter canFilter1;", "declaration")>
  /* store the CAN controller's filter configuration */
  canFilter1.mask = %<block.RTWdata.rxMask1>;

Additional information:

- Windows 7, 32-bit

-Toolboxes installed in the different Matlab versions: MATLAB, Simulink, Embedded Coder, Fixed-Point Designer, MATLAB Coder, MATLAB Compiler(not in 2014a), Simulink Coder, Stateflow, Vehicle Network Toolbox

-Matlab is always started as administrator

-No write protection(read only) on the files