self employment tax

I am a US citizen working for the UN outside of the United States. I file form 2555 (foreign earned income exclusion) and am not subject to self employment tax on the income earned outside of the US. Last year I spent 3 weeks teleworking from the US and must pay self employment tax on the income earned in these three weeks. I have tried to enter that income on Schedule SE but am unable to enter any information on that form. I have also tried to enter the income information on Schedule 2 but am also unable to type on that form.  Please advise what I must do in order to be able to access Schedule SE and report this income.