Implications of Changing Price Control from "S" to "V"

Hi,

I have a material master with "Semi Finished" material type.

However user created it with Price Control 'S' in Accounting 1 view and Material has stock value in it. Now I need to change it to Price Control 'V'.

After it, I changed Price Control 'V" from 'S' type (on dtd. 05.01.2013) i.e. Accounting View showing like this....

Also Costing has been made with Price Control 'S' in May'12 month i.e. Costing 2 View showing like this....

Now if i want to change the Standard Price (Rs. 250.04) as shown in above picture...system showing an error message i.e.

What is the impact changing price control from 'S' to 'V'?

And how to change standard price because we want to run Costing with Price Control 'V'.

Kindly advise.