Need to block adding Purchase Order if Shipping type is not Selected using SPT

Hi experts

am using SAP Business one Ver: SAP Business One 9.0 (9.02.001) PL: 09 HOTFIX1 (32-bit)

i need to block Purchase order to be added if the end user forget to add or select Shipping type

in Logistic Tab

Regrading that i had created a SPT, but it not blocking

pls any one could help me by editing the SPT and solve the issue

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/*Generate error IF WITHOUT Shipping Type */

IF EXISTS (SELECT T0.[DocNum] FROM OPOR T0 WHERE T0.TrnspCode IS NULL and

T0.DocEntry = @list_of_cols_val_tab_del)

BEGIN

SELECT @Error = 18, @error_message = 'Please Select the Shipping type'

END

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Regards

Vinod