Shortend version of Causitive not deininflected

[melink14]

This form is rarely used so you may just want to stick with the more traditional version of the causative form.
ru-verbs - Remove the 「る」 and add 「さす」.
例） 食べる → 食べさす
u-verbs - Change the last character as you would for negative verbs but attach 「す」 instead of 「ない」.
例） 行く → 行か → 行かす
Exception Verbs - 「する」 becomes 「さす」 and 「くる」 becomes 「こさす」.

http://www.guidetojapanese.org/causepass.html