find all the values of x at which the function fails to be continuous

f(x)= 2/(1+cos2x)

I believe the function fails to be continuous when the denominator equals zero(right?)

So wouldn't the correct answer be 2n(pi)+(pi/2) for all integers n? The answer keeps coming up as incorrect.

Could someone please correct me if I'm wrong?

Thank you! I appreciate the help!