webcam won't activate

[meksiAziz]

demo starts with no errors, but the camera won't activate.

[meksiAziz]

EntryPointNotFoundException: _OPSetMultiThreadEnable assembly: type: member:(null)
OpenPose.OPWrapper.OPEnableMultiThread (System.Boolean enable) (at Assets/OpenPose/Modules/Scripts/OPWrapper.cs:42)
OpenPose.Example.OpenPoseUserScript.Start () (at Assets/OpenPose/Examples/Scripts/OpenPoseUserScript.cs:71)

anyone has an idea about this error