form blank unless recordset is changed!!

[Happy YN]

I have a form that has been running perfectly. Its recordsource was a table. I now changed the recordsource to a query based on that table with exactly the same fieldnames etc. but it opens blank, not just empty textboxes etc but no labels and no sight of any textboxes - a big grey area!. the funny thing is that as soon as I change the "recordset type" property -makes no difference to what- then everything appears. however if I save it like that then it still opens blank until I change the recordset yet again
Whats going on?
Thanks

PS I am sorry I put this in the queries section this morning and I wanted it in the forms section

 

[dakcg]

Is your Data Entry property in the form set to Yes

 

[Rich]

Does the query return any records, is it updateable?

 

[Happy YN]

data entry set to yes
query is updateable

someone said that if the query has unique values set to yes then it is the cause and it is true that I have changed it recently but it does not make a difference when its changed to no and anyway why should that create a blank form. I got round it by putting code in the form load event ehich changed the recordset as it loaded but I am not happy with this way
thanks