Exit Function- The Result Returned To Me And Exit (all) Open Functions

I would like to call upon a function until a certain criterion is fullfilled. Then, I would like to have the result returned to me and exit (all) open functions. For value1 = 1 and value2 = 10 I expect value1*value2 = 100. Instead, the routine returnz zero. What is the logical flaw in the code below.

Function testfunction(value1, value2)
If value1 = value2 Then
'Calculating the difference
testfunction = value1 * value2
Exit Function
ElseIf value1 < value2 Then
value1 = value1 + 1
Call testfunction(matrix1, matrix2)
End If
End Function