Now check OB40 for VST whether you have assigned G/L "43020000-Discounts received". Give an appropriate G/L as it is Service tax.
In your Tax procedure there is descrepancy in calculating CST. change the given field to 104 and your CST calculation will be solved.
Now check in OB40 for LUX what you have given G/L account. In OBCN change the Tax type of LUX to "2".
Hope this will solve your issue.
Regards
Binoy