When does it HTML decode?

[Bob Ross]

I am using vb.net to make a website and the data for it (including the control names, values, labels. tooltiptext etc..) are comming from a shared database.
In order to improve security I HTML encoded everything that comes from the database.

But now sometimes it displays correctly (ie &) and sometimes not (ie & ). How can i tell how it is going to come out?
Gridviews do not decode it but labels do but tooltip text doesnt.
Is there any pattern to this?
How do I know what to encode or not?

[kenobewan]

In theory this is all server side code executed on the server and sent to the browser, so the only difference should be in browser interpretation. In practice this should means no difference in controls, so I assume that any lack of decoding is at the programming level. HTH.