seems in struct SlWlanSecParams_t do not have the parameter WEP index in sl_WlanConnect(const _i8* pName,const _i16 NameLen,const _u8 *pMacAddr,const SlWlanSecParams_t* pSecParams ,const SlWlanSecParamsExt_t* pSecExtParams);
typedef struct
{
_u8 Type;
_i8* Key;
_u8 KeyLen;
}SlWlanSecParams_t;
Some AP can set the WEP index like the picture below: