>I have
>
>price1, price2, price3, price4
>
>They must be filled by the user in growing sequence as in the example below:
>
>5.00, 7.00,8.50,10.00
>
>or
>
>1.00, 100.00,1000.00,5000.00
>
>etc
>
>It must be wrong if any variable is not according to the rule, as below:
>
>4.50, 7.00,3.00,10.00
>
>The message ("price 3 is incorrect") must be shown
>
>Seems simple task, but I tried using < and > and could not
>achieve a satisfatory result

IF Price2 > Price1 AND Price3 > Price2 AND Price4 > Price3
  * Everything is OK

ELSE
  DO CASE
  CASE NOT Price2 > Price1
    =MESSAGEBOX( "Price 2 is incorrect" )

  CASE NOT Price3 > Price2
    =MESSAGEBOX( "Price 3 is incorrect" )

  CASE NOT Price4 > Price3
    =MESSAGEBOX( "Price 4 is incorrect" )

  ENDCASE

ENDIF