Solution
The function 'strdup' is not implemented in LabWindows/CVI. There is actually another approach using the 'StrDup' that has been implemented within the toolbox.h. Users may use the following code:
#if defined(_CVI_)
param->key = StrDup(thisParam.key);
#else
param->key = strdup(thisParam.key);
#endif
This implementation will make sure that the proper and existing function is used in the development environment.