A Using problem with Funtion imaqEasyAcquire()

Hi,everybody!

I want to acquire an iamge by function imaqEasyAcquire(),i use a basler camera and it can be see in NI-MAX,my code as follows:

#include "NIIMAQdx.h"
#include "ImageControl.h"
#include <cvirte.h>  
#include <userint.h>
#include "VISONTEST.h"

Image *myacquireiamge=NULL;  

 const char camerename[20]="cam1";

   myacquireiamge=imaqEasyAcquire(camerename);
   imaqDisplayImage(myacquireiamge,1,TRUE);

  When i run the code,it report :

NON-FATAL RUN-TIME ERROR:   "VISONTEST.c", line 237, col 28, thread id 0x0000225C:   Function imaqEasyAcquire: (errorCode == -1074397163 [0xbff60015]). The passed in interface or session is invalid.

If anyone can help me?Thaks so much!