Configurator Web Service - AddItem Method Failing

Hi,

When trying to add a composite product as a child to a parent, it fails at AddItem step. On invoking through UI, the below values are passed to the method AddItem() :
"[Product Id] = 1-87G3H, [Product Name] = EVDO SMS Bundle, [Quantity] = 1, [Integration Id] = 1-AUQWM, [Port Item Id] = 1-3688O, [Port Item Name] = EVDO SMS Bundle". The method gets completed successfully.

And when invoked through the WF, the below values are passed to the method AddItem() :
"[Product Id] = 1-87G3H, [Product Name] = EVDO SMS Bundle, [Quantity] = 1, [Integration Id] = 1-AUNKE, [Port Item Id] = 1-3688O, [Port Item Name] = ".

It fails with the below description :