How to make a line of sigth event only happen once?

I have made it so a sprite spawns another sprite when the player comes in it's line of sigth. The problem is that it spawns the sprite thousands of times infinitly when the player is in it's line of sigth instead of just once like it should. How can i make the Line of sigth spawning only happen once?

I guess using a system trigger once while true event doesn't work?

You could try something like this:

You could try something like this:

Thanks, it,s solved now.