C++ Error in the Code that communicates with pinpad Card Reader - Console application

I have programmed the following which will communicate with a pinpad Card Reader and send a direct command to the reader (not the card apdu). The command will send a plain text key to the card. I am faced with 2 problems actually:

1. When I run the code (console win32 application in Visual Studio 2013) I get the error:

error C2664: 'char CT_data(unsigned short,unsigned char *,unsigned char *,unsigned short,unsigned char *,unsigned short *,unsigned char *)' : cannot convert argument 2 from 'unsigned short *' to 'unsigned char *'

2. I am not sure how to send the direct command to the card reader to insert the key (the key is just a plain text sequence of the type 0026F7993ER365252 - just an example).

This is the code:

#include "stdafx.h"
#include "stdio.h"
#include "ct_api.h"


int main(int argc, char *argv[])
{
       char ret;
       unsigned short ctn;
       unsigned short pn;
       unsigned short sad;
       unsigned short dad;
       int i;

       // REQUEST ICC
       unsigned char command[] = { 0x20, 0x12, 0x01, 0x00, 0x00 };
       unsigned short lenc = sizeof(command);

       unsigned char response[300];
       unsigned short lenr = sizeof(response);

       ctn = 1;
       pn = 1;

       // Initialize card terminal
       ret = CT_init(ctn, pn);
       if (ret != OK)
       {
              printf("Error: CT_init failed with error %d\n", ret);
              return 1;
       }

       sad = 2; // Source = Host
       dad = 1; // Destination = Card Terminal

       // Send command
       ret = CT_data(ctn, &dad, &sad, lenc, command, &lenr, response);
       if (ret != OK)
              printf("Error: CT_data failed with error %d\n", ret);
       else
       {
              // Display response
              printf("Response: ");
              for (i = 0; i < lenr; i++)
                     printf("%02X ", response[i]);
              printf("\n");
       }

       // Close card terminal
       ret = CT_close(ctn);
       if (ret != OK)
              printf("Error: CT_close failed with error %d\n", ret);

       return 0;
}

Any help will be highly appreciated. Thanks :-)