error when knitro used with MSF

Question

Can’t get Knitro to work with MSF express in excel 2010.  It continually says there is an error.  The Knitro solver plugin dll may have problem??  Please advise what can be done.

The directives used to call Knitro are as follows:

           <!-- non linear models-->

      <MsfPluginSolver name="Knitro"

              capability="NLP"

              assembly="KnitroPlugIn.dll"

              interface="Microsoft.SolverFoundation.Services.INonlinearSolver"

              solverclass="SolverFoundation.Plugin.Knitro.KnitroSolver"

              directiveclass="SolverFoundation.Plugin.Knitro.KnitroNLPDirective"

              parameterclass="SolverFoundation.Plugin.Knitro.KnitroNLPParams" />

      <!--Mixed integer non linear models-->

      <MsfPluginSolver name="Knitro"

              capability="MINLP"

              assembly="KnitroPlugIn.dll"

              interface="Microsoft.SolverFoundation.Services.INonlinearSolver"

              solverclass="SolverFoundation.Plugin.Knitro.KnitroSolver"

              directiveclass="SolverFoundation.Plugin.Knitro.KnitroNLPDirective"

              parameterclass="SolverFoundation.Plugin.Knitro.KnitroNLPParams" />

      <!-- Mixed integer linear models-->

      <MsfPluginSolver name="Knitro"

              capability="MILP"

              assembly="KnitroPlugIn.dll"

              interface="Microsoft.SolverFoundation.Services.INonlinearSolver"

              solverclass="SolverFoundation.Plugin.Knitro.KnitroSolver"

              directiveclass="SolverFoundation.Plugin.Knitro.KnitroNLPDirective"

              parameterclass="SolverFoundation.Plugin.Knitro.KnitroNLPParams" />

      <!-- Linear models-->

      <MsfPluginSolver name="Knitro"

              capability="LP"

              assembly="KnitroPlugIn.dll"

              interface="Microsoft.SolverFoundation.Services.INonlinearSolver"

              solverclass="SolverFoundation.Plugin.Knitro.KnitroSolver"

              directiveclass="SolverFoundation.Plugin.Knitro.KnitroNLPDirective"

              parameterclass="SolverFoundation.Plugin.Knitro.KnitroNLPParams" />

      <!-- Quadratic models -->

      <MsfPluginSolver name="Knitro"

              capability="QP"

              assembly="KnitroPlugIn.dll"

              interface="Microsoft.SolverFoundation.Services.INonlinearSolver"

              solverclass="SolverFoundation.Plugin.Knitro.KnitroSolver"

              directiveclass="SolverFoundation.Plugin.Knitro.KnitroNLPDirective"

              parameterclass="SolverFoundation.Plugin.Knitro.KnitroNLPParams" />

      <!-- Mixed integer quadratic models -->

      <MsfPluginSolver name="Knitro"

              capability="MIQP"

              assembly="KnitroPlugIn.dll"

              interface="Microsoft.SolverFoundation.Services.INonlinearSolver"

              solverclass="SolverFoundation.Plugin.Knitro.KnitroSolver"

              directiveclass="SolverFoundation.Plugin.Knitro.KnitroNLPDirective"

              parameterclass="SolverFoundation.Plugin.Knitro.KnitroNLPParams" />