Pricing Conditions for tax behaving differently when manual or automatic

Hello experts.

I am setting up pricing conditions for a tax (z160) that is being sent with the line item in the sales order.

We dont want SAP to calculate the tax as the business rules are in the external system.

in pricing procedure we have z160 set to 0.00. but we send it again z160 with the amount.

The automatic line works ok and determeines the tax code I0 no problem, the manual line in the pricing condition on the sales order determines the tax incorrectly as MWS (not TX) and as input not output tax.

I have been all over ftpx, OB40 vkoa and v/68 and v/06.

How can i get the manual entry to determine the code correctly? they should be the same should they not?

Thanks in advance

Rich G