I am trying to compile the SIM_SolverBullet dll with hcustom, but I get the following error: Creating library SIM_SolverBullet.lib and object SIM_SolverBullet.exp SIM_SolverBullet.o : error LNK2019: unresolved external symbol "__declspec(dllim port) public: float __thiscall SIM_BulletData::getCollisionMargin(void)const " ( __imp_?getCollisionMargin@SIM_BulletData@@QBEMXZ) referenced in function "protec ted: virtual class std::_Tree<class std::_Tmap_traits<int,struct bulletBodystr,s