Condition Syntax

Hello Guys,

In  SAP Webi report ,I defined formula having conditional value

=If   [V_IncDec_Value]>0 Then  " High"

  Else If  [V_IncDec_Value]<0 Then "Low"

  Else If  [V_IncDec_Value]=0 Then "Stayed"

[V_IncDec_Value] has following possible values 

a)  +numbers  ( ex-  +780., + 67.98.  +12827.30 )

b) -numbers    ( ex-  -70, -17.98.  -187.30 )

c)  0

d) "N/A"

Type of variable "[V_IncDec_Value]" shown as Text if variable Edit box

        Suppose i want Compare [V_IncDec_Value] with 0 only when [V_IncDec_Value] having  numeric value .

        So how can i do that . I am thinking to do it via  Nested if or  IsNumeric()  function but not getting proper syntax .

        Please assists me