Given / Find function not working

Dear readers,

I'm having a problem with MathCAD 15 to calculate forces.

I need 15 variabels (Fay Fax Faz, Fby Fbx Fbz, Fcy Fcx Fcz, Fdy Fdx Fdz, Fmmpy Fmmpx Fmmpz) and had 21 formulas. I red somewhere that it had to be 15 formulaes for 15 variables.

So i managed to get rid of 6 formulas.

Still undefined when i try to use the "find" function.

Hope someone can help.

Regards,

Jeroen