Thanks Xander,
Ive tried changing the parameter's in the tool to see if it works, but cant get any results.
I get 2 errors in the results window:-
Error 010098: Insufficient number of points.
Error 010067: Error in executing grid expression.
The location of my points are irregular, but I don't think that would be a hindrance. Ive checked the field details in my tables and all the data types are in Double. My table contains not only X, Y and Z data (Z being the water level in each well), but also contains other attributes which im going to use for the Darcy Flow modelling.