It sounds like you did not enter any taxable income. What income did you enter? If, for example, your only income was Social Security, you do not have to file a return. If you just really want to e-file anyway, a trick you are allowed to use is to enter $1 of interest as income and it will let you e-file.
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**