PICkit 2 VPP voltage level error. Check target & retry operation. Error in PICkit 2
Actually the PICkit we are using is little different from standard PICkits. We placed the IC at the wrong position on the bed.Ours is a 14 pin IC (PIC 16F676). So It gave the errors 


  PICkit 2 VPP voltage level error. Check target &amp; retry operation.
  Error in PICkit 2.


In this PIC kit See here it is quite different, and you can see that we have to place the IC in the 3rd position starting from the top.(For 14 pin IC, 8 Pin IC and 20 Pin IC) . And For the 18 Pin IC, you need to keep it where it is marked as 18.



So that will solve the first error.

And for the second error,


  Invalid OSCCAL Value detected warning.


Just select the following in PICKit Programmer Software:


Select Tools->Check Connection.
Goto Device Family Menu.
Select the correct device family. Ours was Midrange->Standard. (PIC 16F676)
If you are not able to select device manually, check the Programmer menu, and Check "Manual Device Select"
Check if the OSCALL value is not highlighted in Red color.




Now try reading, blank check, erase,etc.

Note: This is for this version (STL035V2.0) Version only. Check Your Pickit for the placing the IC at the correct position.