What are you trying to import into your Coinomi wallet? (your private-keys should start with a L, K or 5)
Did you try to export your private-keys by following this article[1] and using them?
i export my multibit.key file and import in new wallet and yes All was goog.
In which wallet did you import your multibit.key file?
[1]
https://multibit.org/help/v0.5/help_exportingPrivateKeys.html