Main report and sub report parameter in crystal report

[weeraa]

I’m going to use main report and sub report for showing some details.
Main report has InvoiceHeader Part and sub report has invoice detail part.
Invoice Header and invoice detail has 2 SPs.

SP_InvoiceHeader (Use for main report)

ALTER PROCEDURE [dbo].[testSP1]
    @invnoH as varchar(20)
AS
BEGIN
    SELECT * FROM INV_HEADER WHERE INVNO=@invnoH 
END

SP_InvoiceDetail (Use for sub Report)

ALTER PROCEDURE [dbo].[testSP2]
    @invno as varchar(20)
AS
BEGIN
    SELECT * FROM INV_DETAIL WHERE INVNO=@invno 
END

I create the main report and using Insert --> subreport I just add a sub report.
Both reports are used above SPs seperatly.

I just can pass a parameter to sub report using main report. This is the auto genetrated paramenter in sub report. (Pm-?@invnoH). It is showing another parameter in the sub report named @invno which also an auto generated parameter field based on the SP. But I cannot assign @invno to passing parameter.

Simply this equation is not working.
@invno = Pm-?@invnoH

How to pass main report parameter to stored procedure of the sub report? (Up to now I can show passed parameter in the sub report)

I'm using Crystal report version is 8.5