What am I doing wrong with this index match formula with multiple criteria

I'm hoping to create a formula in the highlighted yellow cells in Sheet A that will pull in the result from Sheet B, if it matches two particular criteria.

I've attached an example sheet.

I'm hoping that the formula in B2 in Sheet A, can populate with the correct data in Sheet B if the project id and question id match.

=INDEX('Sheet B'!B2:B7,MATCH(C2&A2,INDEX('Sheet B'!$A$2:$A$7&'Sheet B'!$D$2:$D$7,0))) is giving me an error of #n/a or 0, and can't figure out why

Thanks in advance for the help!