Filter row in form looking up value on a different table

[maiga]

Table 1 name “submission” has columns named [user] [key result 1], [key result 2].

Table 2 name “check in” has columns named [user] [date] [Input 1] [Input 2].

Question:
For some users, [key result 2] is empty. For these users, the check-in form should not ask for [input 2]

I can’t figure out how to filter out [input 2] from the check in form depending on the user and the value of [key result 2].

I tried to apply this filter but it is not working

ISNOTBLANK(lookup(USEREMAIL(), “Submission”, “user”, “Key Result 2”))

Apologies in advance if this is a really simple question.

Thank you,
Maiga