Match Value in Cell to an Existing Column and Return Adjacent Cell Text - excel

Question

I have a spreadsheet containing patients in column a, patient's diagnosis in column b, and their doctor in column c. I have another sheet that has the doctors listed in column a and their practice group in column b. I need a function that will look at each value in column c on sheet 1, match it to the doctor in column a on sheet 2 (Doctors List), and return the practice group to column d on sheet 1. I have tried a few formulas including this one
=IFERROR(VLOOKUP(C2,'Doctors List'!A:B,2,FALSE),"")
but can't seem to get anything to work! It just returns blanks. Please help!
**SHEET 1
Patient Name Diagnosis Attending Physician Practice Group**
Patient A Diagnosis Dr. Smith
Patient B Diagnosis Dr. John
Patient C Diagnosis Dr. Joe
Patient D Diagnosis Dr. Ken
Patient E Diagnosis Dr. Williams
Patient F Diagnosis Dr. Williams
Patient G Diagnosis Dr. Smith
Patient H Diagnosis Dr. Jones
**SHEET 2
Physician Practice Group**
Dr. Smith Practice A
Dr. John Medical Group A
Dr. Joe Practice B
Dr. Ken Medical Group B
Dr. Williams Practice C
Dr. Jones Medical Group C

Answer 1

Try using MATCH and INDEX rather than VLOOKUP
So in D2 of sheet 1:
=INDEX(Sheet2!$B:$B,MATCH($C2,Sheet2!$A:$A,0))
and copy that formula down.
If you're looking to troubleshoot, your existing formula, try using "Evaluate" on the Formulas tab of Excel 2010 which can step you through the calculation.
I've had problems with text fields that have extra spaces after them, so I regularly use the "TRIM" function when doing lookups, or matches.