I'm working on translation for AutoTimer but get this error:

error: 'msgstr' is not a valid python format string, unlike 'msgid'. reson: in the directive number 1, the character 'a' is not a valid specifier.

The original string is this:

Code:
If this is enabled an existing timer will also be considered recording an event if it records at least 80% of the it.
And i have translated it in to:

Code:
Dersom denne er aktivert vil en eksisterende timer vurdere å ta opp en hendelse hvis opptaket er minst 80% av den.
What is wrong?