Problems with events click or clickButton

I've found out now, that it happens only by using the clickButton() method. I replaced ClickButton with Click and DoDefaultAction method and both are working fine. As soon as I use ClickButton mostly the nullpointer exception occurs. I mean this is perhaps a timing problem with windows events when the method was called. It is possible?



My solution for this time is, to use one of the functions above, but I'm not happy about this, because it is very unclear for me why it happens since shortly time... 





Stephanie