Smart value calculation error after is was giving me a result

[AldoCauchiSavona]

This smart value calculation was giving me a good claulation for the whole day, but suddenly, if stopped giving me a value and the variable is empty.

{{#=}} ROUND((({{issue.customfield_10109.diff(fieldChange.to.toDate).days}} / 100) + {{issue.customfield_10109.diff(fieldChange.to.toDate).days}})) {{/}}

The rule log error is:

Unknown unary operator / at character position 10: ROUND((( / 100) + )) .

I double checked the field and before the rule is run, it has a value.Any help please?