How to confirm Despatch if following error ‘Invalid Tax Chapter’ occurs on confirm button click?

Cause: If tax chapter is invalid then system will not allow to confirm the despatch.
System will show error’Invalid Tax Chapter’.
Remedies:
1) User should ensure that tax chapter is populated correctly.
2) User should ensure that Purchase order Tax chapter and Despatch Tax chapter is same.
3) If tax chapter needs to be corrected then user should do Purchase Order amendment and proceed.