hi paul, if what you mean is that the date field on different records all "synchronize" to the same date, i think the most likely cause is that you have specified this field as a "global" field (meaning one value for all records). you just need to change the storage options for the field by unchecking the global storage checkbox.
if, on the other hand, you are trying to have multiple unique dates for the same record (for example, a date for each visit made to the property), then there are at least three ways that i can think of to accomplish this... but probably more.
1. create multiple date fields (this might be best in a situation where there are a relatively small number of discreet dates that only happen once such as "date_purchased", "date_sold", etc).
2. change the storage options for your date field to make it a "repeating" field (i.e. to have the desired number of "repetitions" or different values necessary). this gives you 1 field, but the ability to store multiple different values. this might be better than the first option if you don't have a small fixed number of discreet types of dates, but rather the dates are all of the same type (perhaps visits, or repairs for example). you would then most likely also need at least one more repeating field to contain the "description" for whatever action took place on the corresponding date. you are still limited to the number of repetitions you specify for the field, and if you choose to display all of them on your layout, it could take up a lot of room for information that you might never need.
3. while it is somewhat more difficult to set up, the third option is by far the most versatile and "powerful" option and that is to create a separate table for "visits", "repairs", "payments", or whatever you are tracking, and relate it to the property record. you could then have a portal in the property record to show the related items. some of the advantages to this option are: you can create a virtually unlimited number of related records; you can show as many or as few records as you want by specifying the number of portal rows to display; perhaps most importantly, you can create additional relationships to these related records so that you can find, sort, organize, and summarize them according to date and description or by including additional fields such as the nature of the action (visit, inspect, repair, misc, etc) or the name of the person performing the action.
hope that helps... good luck!