Family table in MS Excel: double value required

[Machinist]

When entering a dimension value in a family table, Excel warning window (Validation failed) pops up and says "double value required". What is a double value? Why does a dimension need a double value? Why is it required by excel? How to bypass this warning message?

[Machinist · Accepted solution]

Found the culprit: conflicting family tables with the same name/reference. Deleted the idx-file and the warnings stopped appearing.
Still no idea what the double value means

[Dale_Rosema]

Don't forget to mark your answer as the correct one for those who will see this post later on.

[KenFarley]

Just a guess, but generally speaking there are "float" variable types that represent real numbers with 32 bits. A "double" real number representation has twice the number of bits (64), higher precision, and can cover a larger range of values. Something in the data you were originally dealing with must have been considered "illegal" by Excel for it to convert to/from a double value.