Structure Conversion between VB6 and C

My VB6 program should call C DLL.
I should pass structure type as a parameter.
Original C structure is like following.

typedef struct strIniSensor
{
const char* theInitFile;
CallBackFunc IniSensorCallBack;
void * CallBackParameters;
}strIniSensor;

I made VB6 side Type Definition like following.
Type strIniSensor '
theInitFile As String
IniSensorCallBack As Long
CallBackParameters As Long
End Type

Is this correct? vensor who provide dll says I can assign NULL to all items(theInitFile,IniSensorCallBack,CallBackParameters) in the structure.