inputting datetime to mssql

Hi, I had this problem that was driving me crazy. I was trying to input a datetime to a mssql table, formated the same way as I use in all my other tables i.e d-m-Y. But no matter which variations of the basic format I tried, it didn't understand the date correctly. In desperation I tried something stupid, inverting the format to Y-m-d, which actually worked. My question is, how can this be possible that datetime fields in two tables in the same datebase requires the input date to be formated in different ways?? And is there any way to fix the odd one out? Regards Henrik Hornemann