How to use PSI to create cross-project link

Hi,

I would like to create task dependencies (links) across projects. 

I used AddDependencyRow method and input LINK_PRED_UID, LINK_SUCC_UID parameters.

It showed the below error after I executed the c# program.

error id="7021" name="TaskNotFound"

I can run my program successfully if I created inter-project link.

Then I think I may need to create external task first.

The taskrow has TASK_IS_EXTERNAL and TASK_EXT_PROJ_UID properties, but it doesn't have TASK_EXT_TASK_UID property.

Do you have any suggestion?

Thanks.