Try this:
@startuml
scale 0.6
(*)-->if "cond1" then
-->[true] "Do Action1"
--> a1
else
-->[false] a1
endif
a1 --> if "cond2" then
-->[true] "Do Action2"
--> a2
else
-->[false] a2
endif
a2-->(*)
@enduml
My understanding of what you want is that if the cond1 is satisfied, then you want to do something and if not you don't want to do the action. However, in either case, you want to come to cond2. Sounds right?
- Karthick S.