String parameter not passing correctly to GP service

Question

I have a model where the user selects a string from a drop down list which is used to select a building point and run a series of trace operations. This works fine on desktop, but keeps returning the same data when ran from the server. It turns out that when the process is published after being run from 'any building', it only uses that building name when run from the server, no matter what is selected by the user. It seems that the request is sending the correct string, but the GP service is not accepting it or changing the input parameter string.

I do not understand why the input parameter does not change based on the selected input. I am using a field seletion tool I found online that seems to work perfectly when run on the desktop.

Does anyone have any idea as o why the input is not being changed??

EDIT: He is the validation code

import arcpy
class ToolValidator(object):
  """Class for validating a tool's parameter values and controlling
  the behavior of the tool's dialog."""

  def __init__(self):
    """Setup arcpy and the list of tool parameters."""
    self.params = arcpy.GetParameterInfo()
    self.fcfield = (None, None)

  def initializeParameters(self):
    """Refine the properties of a tool's parameters.  This method is
    called when the tool is opened."""
    return

  def updateParameters(self):
    """Modify the values and properties of parameters before internal
    validation is performed.  This method is called whenever a parmater
    has been changed."""
    if self.params[0].value and self.params[1].value:
      fc, col = str(self.params[0].value), str(self.params[1].value)
      if self.fcfield != (fc, col):
        self.fcfield = (fc, col)
        self.params[2].filter.list = [str(val) for val in
                                        sorted(
                                          set(
                                            row.getValue(col)
                                            for row in arcpy.SearchCursor(fc, None, None,
                                                                          col)
                                              )
                                           )
                                      ]
        if self.params[2].value not in self.params[2].filter.list:
          self.params[2].value = self.params[2].filter.list[0]

  def updateMessages(self):
    """Modify the messages created by internal validation for each tool
    parameter.  This method is called after internal validation."""
    return

Answer 1

I figured out the issue, but I can't say I fully understand it. On the far left side of my screen shot, you can see a wMain layer, this was being used to select the pipe sections intersecting the building points. This wMain layer was one that was loaded into the MXD I was working off and that gets copied to the server. Turns out the correct building points were being passed and used in the GP service, but after being published, the wMain layer data would not get overwritten. Whatever building it would run as, those were the only sections your would ever get.

I instead used the source FC from the SDE and created a layer from it in the model, and ran the select location off that layer. I assume this is working be it is always making a fresh layer from the data, but I don't really understand why. The layer in the MXD is referencing the same data, so why would this not work over creating a new layer?

@KHibma helped me to rule out the script tool.