Possible implementation of the "message" design pattern

[dodo76]

Hi all,
if an abstract class has a method

abstract public void Method(IParam parameter);

where "IParam" is an interface (even possibly empty),
what is conceptually wrong with a derived class trying to implement

public override void Method(ISomeObject parameter)

where the interface ISomeObject derives from IParam ?

I was trying to follow the design pattern "message" here.

Thanks.