Just got hold of and fitted a 90 spec rst motor into my S1 after melting a piston on the old one.

The engine has done about 4-5000 miles since a full rebuild (stage 3 head, low comp forged pistions etc etc) but has been sat out of a car for a while.

Just got the swap finished this evening but after cranking it over oil pressure light stays on. Taken the oil feed hose off of the turbo to see if anything is coming out, but nothing.
Just done and oil and filter change and the oil is Mobil1 15W50 Fully synthetic.

Have checked there are no leaks anywhere, all hoses connected in the right places etc. The only thing i can think of is the oil pickup or oil pump out working.

Does this sound right? Or any other ideas?