Installes Excel 2013, now getting error message , when open excel we have Atlas.Ti 6 sfwr

we have installed atlas .ti 6 version swfr , and Microsoft 2013, also, and every time I open excel getting this error message ,
can some one please advise how to fix this,

below is msg

A problem occurred while an add in -was being initialized (failed)
Add in is built with excelDna and is being loaded from C:\Atlas6\Client\atlas6.formulas threaded.xll

any help will be great,
since you guys are really expert

thanks in advance

and cannot open Atlas.ti either . its not working

thanks again

I am not sure if any one familiar with Atlas.ti