Link Error when using OpenNurbs lib

In my system, building a windows console app with opennurbs_public_staticlib.lib is successful at most of time.

However, sometimes, I got link error when I try some of functions.

For example,if I use the following two lines;

double t1, t2;
m_curve.GetDomain(&t1, &t2);

I got error LNK2001: unresolved external symbol "public: int __thiscall ON_Curve::GetDomain(double *,double *)const

Another example, if I use:

ON_3dPoint p;
m_curve.GetCV(i, p);

The link error is:
LNK2001 unresolved external symbol “public: __thiscall ON_3dPoint::ON_3dPoint(void)” (??0ON_3dPoint@@QAE@XZ) …

I cant understand why some openNurbs functions work, while some will fail.

Anyone knows the possible reason ?

Thanks,

What version of Visual Studio are you using? Are you using openNURBS 6?

– Dale