[amibroker] Entry code

[t_ohrt]

Hi,

I want to limit entries to once a day within a daytrade system. A long 
position should be taken only at the first occurrence 
of "LongEntryCond". The code below results in no entries at all. What´s 
wrong with it?

Buy= LongEntryCond AND ValueWhen(LongEntryCond, DateNum())<DateNum();


Regards,
T.O.