Mysql or MSSql from Xamarin Forms

I'm building an cross-platform app with Xamarin Forms. Im having a lot of trouble loading packages to access databases.

I don't seem to be able to install either System.Data.SqlClient or MySQL...... or Pomelo.

Seems to be something to do with .NetPortable, and profile 259.

Example:

Could not install package 'Pomelo.Data.MySql 1.0.0'. You are trying to install this package into a project that targets '.NETPortable,Version=v4.5,Profile=Profile259', but the package does not contain any assembly references or content files that are compatible with that framework. For more information, contact the package author.
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Help? What am I doing wrong?