Created a Button in Apex , when clicked should create an AR invoice in EBS, but it errors out

 Hi,We are planning to create a button and upon clicking on this button we are caalling apis to create ar invoices in oracle ebs.

But what i saw is as follows.

when the procedure which gets executed on the click of the button in apex, if the procedure is a simple one it executes but for calling an api i need to use 

MO_global.init and mo_global.set_policy_context,fnd_global.apps_initialize procedures given by oracle.

when i use these  , and when i click on the button , it gives process errored.

Please help me on how to call an API when we click on a button created in apex.