cst error port mode

hello
Someone can help me for this problem ?
Actually I work with 2 versions of CST software one old and one new.
I have done a model in the new version.
then
I need to transfert my model realized in the new version to the old version of CST.
but this old version cannot read the file from the new version. So I import this simulation ( from new to old ) using a new format :SAT
then when I simulate the imported file in the old version i have this error message
* the propagation constant of mode 1 is zero cannot continue
* the port mode eigensolver failed.
maybe the the change of format delete some informations that the old version need, I don t know.
If someone know why I have these error message thanks for his help.

hi lefrancais,
Generally a model established in a new version can not be correctly opened with an old one, for many new elements are added when a new CST version is released and these may not be "recognized" by the old version.
I was also puzzled by this problem several times and had to remodel them. So now i choose to use a relatively old version, though sometimes not that convenient.

havnt met such problems

hi lefrancais,
why do you need to go back to an older version? This shouldn't be necessary. especially if the newer version has fixed some problems found in the older version.
Has the number of mesh cells changed? I suspect so but check this. There were some changes made regarding the global mesh settings.
What versions are you referring to anyway?
aw