Your parameters must be bad, either that or the engine implementation has a bug.
And it seems the fifth argument is wrong, it’s supposed to be the actual radius of the cone, not the angle of it. Maybe the third parameter is wrong as well depending on what AttenuationRadius refers to. The way you have it now OuterConeAngle is probably way smaller than what it should be. So you’ll first have to compute the value for the fifth argument based on the other values you have.
It should be something along the lines of