You might be affected by a bug in the Spreadsheet feature, that I presume that is fixed since a few weeks ago in current code. Which Tiki version are you using?
can you try to reproduce the issue at http://demo.tiki.org ? (on whichever supported version that best resembles your tiki version?)
If you can confirm that this is a bug, you are more than welcome to add the bug report yourself, against the Spreadsheet feature, at:
and maybe that is a bug already reported? You can check that for instance at
Last, but not least, welcome to the Tiki Community!