93 Blazer 4 X 4 question

I have read all of the posts on troubleshooting my 4 X 4 system...electronic shift model (lights on dash)...I have verified that the vacuum actuator works...actuator cable is free and not bound up...replaced front axle status switch...replaced vacuum switch on transfer case...verified no holes in vacuum lines anywhere...will not shift into 4 hi or 4 low...both lights on dash switch light up and stay on...transfer case makes it's noise when shifting to 4 lo but and actuator is engaged, but no 4wd...can anyone help?