CS0266: Cannot Implicitly Convert Type 'object' To 'bool'. An Explicit Conversion Exists (are You Missing A Cast?)

Using OnSelected on the SqlDataSource----
here is my currect code:
private void On_Load(Object sender, SqlDataSourceCommandEventArgs e)
{
if (e.Command.Parameters["@DueDate"].Value = "NULL")
{
e.Command.Parameters["@DueDate"].Value = "0000-00-00 00:00:00.000";
}
}

I am trying to change the value from  NULL(in a datetime field) to "0000-00-00 00:00:00.000" for use on the page.
Any ideas, suggestions, or thoughts would be greatly appreciated!

,Gary
"we truly fail, only when we quit."