Problem with 'set_execution_parameter_value' and project parameter

Hi,

In my SSIS Package I'm using a Project Parameter of type string. I want to set this parameter from stored procedure by using "set_execution_parameter_value". Here is my code.

DECLARE @customerFilter sql_variant = 'N0000' 
EXEC [SSISDB].[catalog].[set_execution_parameter_value]
        @exec_id,
        @object_type = 20,
        @parameter_name=N'CustomerFilter',
        @parameter_value = @customerFilter

Msg 27147, Level 16, State 1, Procedure check_data_type_value, Line 26
The data type of the input value is not compatible with the data type of the 'String'. 

Same when I use varchar(8000)

DECLARE @customerFilter varchar(8000) = 'N0000'