Electrical connection of new gauges

[HandyAndy]

Help please

I have bought an Oil Pressure gauge & Oil Temp gauge.......

bought the correct Sandwich plate thinghy & installed it correctly, installed the sender units etc into it.

Mounted my new gauges in the dash, they light up when side & dipped lights are turned on

However.....the instructions............3 connections to make

1) connect "S" direct to sender unit at oil filter end = done that
2) connect "-" to engine negative earth = done that
3) connect "+" to ignition live terminal = done that

The problem = the temp gauge isn,t reading a temp....
the pressure gauge goes off the scale

what am I missing? ( sorry if its obvious, me & electrickery just don,t mix )

cheers
andy