Date time insertion

I am trying to insert both the date and the time into a datetime field.

If the field datetime in table v1 is dt, then the following successfully
inserts the date into the datetime field:

insert into v1 (date) values ('19990401') ;

However, if I also wanted to retain the time of day, the following does not
work:

insert into v1 (date) values ('199904011530') ;

Any hints?

Thanks in advance.

Regards - Bob Kruger