compile error

[ap <apostop@xxxxxxxxx>]

I have the following #define in my code
#define SWAP64(p) ( (*(unsigned _int64*)(p)) = _byteswap_uint64(*(unsigned 
_int64*)(p)))
When I compile I get the error: expected primary-expression before 'unsigned', 
when I use SWAP64

Does anybody have any idea?
Thanks