Question: Is my system of equations unsolvable?

Hi.

I'm working on an electronics project currently. In that project I have been trying to solve a system of inequalities, as shown by the picture from Maple below:

restart;

R__1 := 1;
lign1 := V__i/(R__4*(1/R__1 + 1/R__2 + 1/R__3 + 1/R__4)) = C*(k__1 - R/R__C + R);
lign2 := V__i*(1/R__1 + 1/R__4)/(1/R__1 + 1/R__2 + 1/R__3 + 1/R__4) = C*(k__2 - R/R__C + R);
lign3 := V__i*(1/R__2 + 1/R__4)/(1/R__1 + 1/R__2 + 1/R__3 + 1/R__4) = C*(k__3 - R/R__C + R);
lign4 := V__i*(1/R__3 + 1/R__4)/(1/R__1 + 1/R__2 + 1/R__3 + 1/R__4) = C*(k__4 - R/R__C + R);
lign5 := V__i*(1/R__1 + 1/R__2 + 1/R__4)/(1/R__1 + 1/R__2 + 1/R__3 + 1/R__4) = C*(k__5 - R/R__C + R);
lign6 := V__i*(1/R__1 + 1/R__3 + 1/R__4)/(1/R__1 + 1/R__2 + 1/R__3 + 1/R__4) = C*(k__6 - R/R__C + R);
lign7 := V__i*(1/R__2 + 1/R__3 + 1/R__4)/(1/R__1 + 1/R__2 + 1/R__3 + 1/R__4) = C*(k__7 - R/R__C + R);
solve({lign1, lign2, lign3, lign4, lign5, lign6, lign7}, [R__4, R__2, R__3, R__C, R, C, V__i]);

Here's a picture as well:

However, the solution is simply that V_i = 0 and C=0, which is not really helping me. Am I doing something wrong here or is my system of equalities simply unsolvabe?