The gain control is not available for the selected camera
This VB example uses the minimum and maximum gain values to initialize the slider control:
Private SubForm_Load() Slider1.Min = ActiveDcam1.GetGainMin
Slider1.Max = ActiveDcam1.GetGainMax
Slider1.Value = ActiveDcam1.Gain
If the currently selected camera doesn't support software gain control, the method will generate an error.