inn.applyMethod() doesnot work at all :(:(:(

I am trying to call server method(C#) from client method(Javascript) but applyMethod() doesnot work at all......... :(

var ctx = this.document.thisItem;

var inn = ctx.getInnovator();

var branches = inn.applyMethod("SFT_LoadBranchesServer","<source_id>"+document.thisItem.getID()+"</source_id>"