Need To Edit This Formula

[Esmatullaharifi]

Hi Dears!
I am using the (IIf(([Studies1]>0) And ([Studies2]=0) And ([Studies3]=0),[Studies1],IIf(([Studies1]>=0) And ([Studies2]>0) And ([Studies3]=0),[Studies2],IIf(([Studies1]>=0) And ([Studies2]>=0) And ([Studies3]>0),[Studies3],0))))
to show the value of studies1 when other fields are zero and this field has a number greater than 0 and show the studies2 value when the studies1 is equal or greater than 0 and so on the value of studies2.
The Problem is here i want to use this formula work with empty strings (" ") instead of 0 for this i used the (IIf(([Studies1]<>"") And ([Studies2]="") And ([Studies3]=""),[Studies1],IIf(([Studies1]>=0) And ([Studies2]<>"") And ([Studies3]=""),[Studies2],IIf(([Studies1]>=0) And ([Studies2]>=0) And ([Studies3]<>""),[Studies3],0)))) Formula for my purpose but its not working.
Please Help Me To Solve This Problem.
Read For More Information:
Main Purpose of using formula is this that I want to do the following work with the function.
When I type a number greater than or equal to 0 in the Studies1 field and keep the two other (Studies1 and Studies2) fields empty the result must be the value of Studies1 field.
When I type a number greater than or equal to 0 in the Studies1 field and also type a number greater than or equal to 0 in the Studies2 field and keep the one other (Studies3) field empty the result must be the value of Studies2 field.
When I type a number greater than or equal to 0 in the studies1 field, type a number greater than or equal to 0 in the studies2 field and also type a number greater than or equal to 0 in Studies3 the result must be the value of Studies3 field.

[ranman256]

Assuming the Studs are fields.

Function CalcFlds(Stud1, Stud2, Stud3)
Dim vVal
Select Case True
    Case Stud1 >= 0 And IsNull(Stud2) And IsNull(Stud3)
       vVal = Stud1
    
    Case Stud1 >= 0 And (Stud2)>= 0 And IsNull(Stud3)
       vVal = Stud2
    Case Stud1 >= 0 And Stud2 >= 0 And Stud3 >= 0
       vVal = Stud3
End Select
CalcFlds =vVal
End Function

[Esmatullaharifi]

Thanks Dear RanMan My Problem Is Solved

[ranman256]

good, but I had an error on the 2nd Case. (corrected above)