factory sigma turbo wastegate issues

[turbol200]

so I have a gd wagon that has a 4g54 and efi, its currently getting an adaptronic and turbo added to it, I have run into a problem with the wastegate,(its a factory sigma turbo manifold and gate) when bolted together there is a gap in the gate plunger and its sea, would only be a couple of mm, im wondering if there is a problem with my wastegate or am I missing some thing like a removable valve seat, cheers any help would be appreciated , and if any one has info of any other gates that may be used to replace the sigma one that would also be awesome cheers