I have setup an orthogonal designs in R package DoE.base(fract.design <- oa.design(nlevels=levels.design). The function (oa.design)will look up into a library of orthogonal designs. If orthogonal design isn't a available , the function will just return the full factorial design, and therefore I have to call the optFederov function. I have tried the following two codes:

• oa.design(nlevels=c(2,2,3))
• oa.design(nlevels=c(2,2,4))
  

The first doesn't have a solution but the second one does works with an orthogonal and balanced design. Could you help explain why the first code is not working?