I'm a full time employee but have a small business under a sole proprietorship. I have a 401K at work, an IRA with Vanguard, and a SEP with Vanguard. Does SEP 25% apply?

I tried to enter 25% for SEP and Turbo H&B won't allow any contributions. I haven't entered any other  retirement data, yet, so I don't know why it won't allow a SEP contribution.