RIA DomainService Query with parameters LightSwitch

I am trying to use RIA services in LightSwitch but I get an error when the query in the DomainService has a parameter because the query is not imported into LightSwitch.

All the other queries are fine.

The error I get when attac开发者_开发技巧hing the data source in the Wizard window is

The parameter 'ID' in query 'AllRecordsbyId' is not a nullable type. This query will not be imported.

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make the parameter nullable:

public IQueryable<CategoryTree> GetAllCategoryTree(int? AllRecordsbyId)
{
}