Grabber - statics example

Hello,

We should get the length x , when the grabber can just hold the box.

grabber

I made two moment equations:
M1

M2

Then I put them together into one equation: m1m2

And from that equation I found out x: x

Unfortunately the result seems to be wrong. Can you please help me? Where I made the mistake?

72091_priklad.png

$\Sigma M_H = 0$

$(x\sin \alpha)(\frac{1}{2}G) + \frac{1}{2}G(\frac{1}{2}b) = \dfrac{G}{2\mu_0}(l_1 + l_2)$

$x = \dfrac{2(l_1 + l_2) - \mu_0 b}{2\mu_0 \sin \alpha}$