We have recently upgraded From Solid works 2010 to Solid works 2013..We have some custom Toolbox parts .After upgrading the 2010 toolbox to 2013 ,We are getting the "toolbox\swtoolbox.dll cannot be loaded.Either the add-in or one  of its components is missing" Error .Please help me to resolve this error

Please suggest me How to upgrade the Solid works 2010 custom Tool box to Solid works 2013 Toolbox??

Thanks in advance

Lingahetty