Invalid use of Null

[Federica Pavese]

When I want to recover a datum from a database, which contains a Null value, the program shows an error message: Invalid use of Null.

For example:
Dim rstTemp as Recordset
sentence = "SELECT * FROM aaaa WHERE city='MZA'"
...
txt_phone.Text = rstTemp!phone

The data field "phone" has a null value. (no 0, no "")
¿What can I do? Thanks in advance!

[Federica Pavese]

I have the solution : the IsNull function.