Hey Dennis,
I've gone back and looked over this issue again. Still I am not able to produce this error, did you fill in the whole screen?
Usually this error means there is a required field that’s missing. Double check that you have filled in all the fields and then try and save.
If you get an error, copy and past it into the forum. Also what button are you selecting when you get this error.
Save, Save and New, Save and Close???
Once we get some more information ill be able to let you know if it's a user related issue.