Transact SQL :: Creating Stored Procedure With Cursor Loop

I appear to be having an issue where the @LetterVal and @Numeric variables aren't resetting for each loop iteration, so if no results are found, it just returns the previous loops values since they aren't overwritten.  Below is the stored procedure I've created:

ALTER PROCEDURE [dbo].[ap_CalcGrade] 
-- Add the parameters for the stored procedure here
@studId int,
@secId int,
@grdTyCd char(2),
@grdCdOcc int,
@Numeric int output,

[Code] ....

And below is the "test query" I'm using: 

--  *** Test Program ***
Declare @LetterVal varchar(2), -- Letter Grade
        @Numeric   int,        -- Numeric Grade
        @Result    int         -- Procedure Status (0 = OK) 
Execute @Result = dbo.ap_CalcGrade 102, 86, 'QZ', 3, 

[Code] ....

This is resulting in an output of: 

A+ 97
A+ 97
C- 72

but it should be returning the output below due to the 2nd data set not being valid/found in the sp query:
 
A+ 97
No Find
C- 72

I'm sure this is sloppy and not the most efficient way of doing this, so whats causing the errant results, and if there is any better way I should be writing it.  Below is the assignment requirements:

Create a stored procedure using the STUDENT database called ap_CalcGrade that does the following:

1. Accepts as input STUDENT_ID, SECTION_ID, GRADE_TYPE_CODE, and GRADE_CODE_OCCURRENCE
2. Outputs the numeric grade and the letter grade back to the user
3. If the numeric grade is found, return 0, otherwise return 1
4. You must use a cursor to loop through the GRADE_CONVERSION table to find the letter grade