DB Data Controls don't lett me modify data

After linking a dbgrid showing the contents of one table to a dbedit
showing a field in another table with a common field using two queries and
two datasets, I am able to view the one to one relationship but not to
modify the data in the dbedit.  All readonly properties are set to false on
all tables, etc.  What could be forbidding me from modifying the data?  I
am using a tabbed notebook but the components in question all reside on the
one page of the notebook.  If anyone has experienced the same problems and
knows possible solutions, pleas notify me via email.

Thanks.

Jeff