CST or VAT which on is applicable

Dear Sir,

my case is

1) i received the Purchase order From UP Customer for manufacturing of Moulds and delivery terms mentioned in PO are Delivery at UP Plant

2) After Manufacturing, we raised the bill to UP Customer by Charging him CST @ 2%.

3) but later on as per instruction of UP Customer, we transfer the finished mould within the state to our branch for manufacturing of Customer specified goods by using the mould.

4) Here, Customer prepare the Seprate Loan Document which is Clearly mentioned that the Proporty (i.e. Moulds) are in the name of customer of UP and we have to use only for Mfg. purpose of customer.

5) Now, Customer claiming that CST is not chargeble on this transaction and we must charge the VAT on the same

Please suggest, which tax i can charged.