I would set it up in a lab and test it first, if possible.Sounds like you have the correct Network Service Module and license.

Here is the guide on configuring it with IOS 15.0(1) http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/15-0_1_se/configuration/guide/3750xcg/swmnetflow.html 

Can you run SH VER and post that for us?

Jay Brown wrote:cadet alain wrote:Hi,http://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/15-0_1_se/configuration/guide/3750xcg/swmnetflow.html"Flexible  NetFlow is supported only on the Catalyst 3750-X and 3560-X sw...