work list connected with holiday plan and skills table

hi everybody.
I've got some problem. I need to count how many of employee will be at work with knowledge of every process. This value is based on value from holiday plan and skills table. More explanation you can find in att. file.

I know how to count how many employee know the process. I use function formula =COUNTIF(skills!D12:D35;">0") but i've got problem how to connected this with plan of holiday. Also every pearson know know different process (i've got 20 process on the list).

If someone can help me it'll be great or even give some idea how to do this. I was trying to find something similar in net but without any resluts. PLEASE help me.

hi FDibbins,
Thank you for your post, but it doesnt work. Please see the attachement. On holiday plan we can see that 4 pearson are on holiday, but in sills table they got 0 in skills table in proces1. So in work plan sheet value in C6 should be 5, becouse no one from emplooye with knowledge about process one is on holiday 1.1.2013.

pl see the attached file with formula.

Thank you very much for compliments.