problem with validationsummary and custom controls

[Phl]

Hello, can some one help me with this problem?

I have a mainpage with validationsummary control. usercontrols are
loaded dynamically. I do validation in these usercontrols. Some of
them I use requiredvalidation others I use customvalidation.

Here is the problem. The error messages from my requiredvalidation
controls are loaded(or redisplayed from postback) properly. While the
customvalidation error messages are only shown in the
validationsummary control in the first time, but after the next
postback they no longer gets displayed. So I guess I need to run my
customvalidaiton everytime?

I really don't understand why they aren't persisted in the viewstate.
Does anyone know what the bestway for me to integrate the
customvalidation with the validationsummary?