SQL money datatype is not recognized

[n8900498]

public void Collection_Save(string PMN,string CollectionNotes,WTF?! ReserveBalance,string UpdatedUser)

The actual SQL sproc:
CREATE proc [dbo].[Collection_Save]
@pmn nvarchar(15),
@CollectionNotes varchar(max),
@ReserveBalance money,
@UpdatedUser varchar(50)