USB connected to TM4C1294NCPDT

My requirement is to check, if the USB is connected to my device or not. 

I have implemented the following code from example drivers;

USBMSCHFatFs_Handle usbmschfatfsHandle;
	USBMSCHFatFs_Params usbmschfatfsParams;
	USBMSCHFatFs_Params_init(&usbmschfatfsParams);
	usbmschfatfsHandle = USBMSCHFatFs_open(Board_USBMSCHFatFs0,USB_DRIVE_NUM,&usbmschfatfsParams);
	    if (!usbmschfatfsHandle)
	    {
	        sprintf(txBuffer,"Error starting the USB Drive\n");
	        UART_write(uart,txBuffer,strlen(txBuffer));
	    }
	    else
	    {
	        sprintf(txBuffer,"\t\t\tDrive %u is mounted\n", USB_DRIVE_NUM);
	        UART_write(uart,txBuffer,strlen(txBuffer));
	        USBMSCHFatFs_close(usbmschfatfsHandle);
	    }

But when I remove, the USB drive, also it is showing Drive is mounted. Help needed