Looking for more than one expression in a value

[Roger Meili 2]

I try to find different expressions in a data string. I use the IF, OR and FIND functions. If I am looking for just one expression it works perfectly but if I try with the IF-Formula to find more expressions, it doesn't work. Does any body know why? That's the formula I use:

IF(OR(FIND("KG", Contact.recent_conversion_event_name), FIND("event", Contact.recent_conversion_event_name), FIND("webinar", Contact.recent_conversion_event_name)), NULL, Contact.recent_conversion_date & " - " & Contact.recent_conversion_event_name & " - " & Contact.what_are_your_major_challenges_ & " - " & Contact.open_answer & " - " & Contact.recent_webinar)

By the way, the formula checker shows all correct.