Getting unexpected result for sum operation

[venkatbatchu]

Hi ALL,
I have been getting some unexpected result with this function which is only getting c=a+b

Code:

Function sum(a,b)
   c=a+b
   msgbox c
End Function
m=datatable.GetRowCount
For i=1 to m step 1
datatable.SetCurrentRow(i)
a=datatable.Value(1,1)
msgbox a
b=datatable.Value(2,1)
msgbox b
Call sum(a,b)
Next

when i perform this function i am geting the results like
ex: a=12 b=5
it is giving the result 125 for c , it has to give 17 (C=A+B)
if c=a-b, a*b then it is giving as expected.
Please let me know whether this is correct one or not....