Xenko android error

[MyGameActivity.cs(6,13)]: Error:The type or namespace name ‘Starter’ does not exist in the namespace ‘Xenko’ (are you missing an assembly reference?)
[MyGameActivity.cs(14,35)]: Error:The type or namespace name ‘AndroidXenkoActivity’ could not be found (are you missing a using directive or an assembly reference?)
[MyGameActivity.cs(16,33)]: Error:‘MyGameActivity.OnCreate(Bundle)’: no suitable method found to override
[MyGameActivity.cs(24,33)]: Error:‘MyGameActivity.OnDestroy()’: no suitable method found to override