K2 API's DeleteProcessInstances deletes the wrong process instance

Hi guys,

I have been using the method DeleteProcessInstances for quite some time now and it did behave accordingly. However, when I tried to use it again, I get an exception stating that the process instance '28012' is not present in K2.  Funny thing is, the process instance passed to the method is obtained from matching ids from a list against K2's GetProcessInstancesAll.

Can somebody help please.

Thanks.