Type error switching from .m to .mm

I encountered this error:

cannot convert 'V_DTLPROMO_BTN_FN_T' to 'V_DTLPROD_BTN_FN_T' in argument passing

in code line:

[ m_vPromoDetails   changeButton : V_DTLPROMO_BTN_2 btnFn : V_DTLPROMO_BTN_FN_ADD ]; 

Both arguments are of type V_DTLPROMO_BTN_T & V_DTLPROMO_BTN_FN_T which is are enum declared in the .h file. Things were working fine until I changed the implementation file extension to .mm from .m to accommodate some C/C++ related code.

Prototype declaration

- ( void )changeButton : ( V_DTLPROMO_BTN_T    )button 
             btnFn : ( V_DTLPROMO_BTN_FN_T )btnFn

Enum definitions

    typedef enum
{
  V_DTLPROMO_BTN_FN_NONE        =   0,   /**< None                       */
  V_DTLPROMO_BTN_FN_RECOMMEND   =   1,   /**< Recommend                  */
  V_DTLPROMO_BTN_FN_ADD         =   2,   /**< Add                        */
  V_DTLPROMO_BTN_FN_DELETE      =   3,   /**< Delete                     */
  V_DTLPROMO_BTN_FN_LOCATE      =   4,   /**< Locate                     */
  V_DTLPROMO_BTN_FN_BUY_NOW     =   5,   /**< Buy Now                    */
  V_DTLPROMO_BTN_FN_SHOPPED     =   6,   /**< Shopped                    */
  V_DTLPROMO_BTN_FN_TWEET       =   7,   /**< Locate                     */
  V_DTLPROMO_BTN_FN_NUM         =   8    /**< Number of function choices */

} V_DTLPROMO_BTN_FN_T;


    typedef enum
{
  V_DTL开发者_如何学JAVAPROMO_BTN_1     =   0,   /**< Button: 1         */
  V_DTLPROMO_BTN_2     =   1,   /**< Button: 2         */
  V_DTLPROMO_BTN_3     =   2,   /**< Button: 3         */
  V_DTLPROMO_BTN_NUM   =   3    /**< Number of buttons */

} V_DTLPROMO_BTN_T;

V_DTLPROD_BTN_FN_T is an enum declared in another class.My detailpromo class was somehow getting confused by that enum in detailprod class.I noticed that the function names were same in both the classes ,so I tried to change the function name from changeButton to changeButtonForPromo.That did the trick and errors were removed.Still havent got the technical explanation for that.