Set Property Object, Error -17335

I'm trying to write a sequence that'll help me set privileges for new groups. Whenever I run my sequence, I get the following error: 

-17335; Property object cannot be added.

All I'm doing in my sequence is:

1. Creating a new user
2. Setting the name
3. Setting the privilege using the SetPropertyObject method

I've attached a snippet of my sequence, but the error occurs with the following statement.

Locals.UserRef.AsUser.Privileges.SetPropertyObject(Priv_GrantAll, PropOption_NoOptions, Parameters.Privileges.GrantAllFlag)

I've used this method in other sequences, but I can't seem to figure out whats causing the error here. Any help or pointers to where I could look would be appreciated.

I'm using TestStand 2016 (32-bit).

Thanks,

Luis