There must be transformations for pager specified as there is Universal Pager used within this web part. You need to create transformations and then specify their name into properties with following names:
PagesTemplate
CurrentPageTemplate
SeparatorTemplate
FirstPageTemplate
LastPageTemplate
PreviousPageTemplate
NextPageTemplate
PreviousGroupTemplate
NextGroupTemplate
LayoutTemplate
You may optionally see sample transformations in this web part's configuration section at ~/Examples/Webparts/Full-text-search/Smart-search-dialog-with-results.aspx page in sample CorporateSite (the one based on Portal Engine).