I am using latest version of Captivate 2019.
I want assign value to variable on slide end. For the this i am checking currentframe value for the validate.
See below Screengrab for more information.
You don't tell which event is triggering this action, nor why you choose to use cpInfoCurrentFrame. Using an exact frame number is a tricky approach, because you are never completely sure it will not be the previous or the next frame. If you did explain the goal, would be able to help you better. I have been using this system variable a lot but always with care, realizing the its population maybe be slowed down.
I don't think what you are doing in this case is a very good idea. If the current frame happens to be any number other than the one you are testing for then the Assign action will not be performed.
How are you determining that at the very moment you are executing this Conditional Action the value of the system variable cpInfoCurrentFrame is going to be this specific number?