Convert text fields to a Date Field

I have two text fields:  [Publication Month] and [Publication Year].  I want to know convert this into a Formula Date Field called [Publication Date].  I will use the publication day as the 1st for every case.  This is the formula I tried but it didn't work.

ToDate([Publication Month Long] & "1, " & [Publication Year])

Can anyone help? It may just be simple formatting??

Thanks.