Error message

[Donna]

I created a simple access database to store information,
and included a command button to append the current table
to a cum file and its returning an error that "the table
is already opened exclusively by another user, or it is
already open through the user interface ad cannot be
manipulated prgrammatically. In the macro that runs, the
form is closed first before the append query runs. I
created this database three times because I thought it was
corrupted now I don't know what the problem is.
Help!!!