Hello Vishnu,

Thank you for contacting Infragistics!

Using two different version of the Infragistics controls isn’t recommended or possible. Attempting to use multiple versions in the sample project will cause conflicts and the controls won’t know what version of the assemblies to use. Since you are using v12.1 I would recommend that you instead just upgrade to that later version as all the controls that are in v12.1 are in later version except for the WebSpellChecker which was removed in v15.1 and spell checking is now done through the WebHtmlEditor.

Please let me know if you have any further questions concerning this matter.