Does it seem missing an other solution ?

There sure are more solutions missing than just one.

You have 5 equations for 6 variables - there is an infinite number of solutions.

[EDIT] Had my reply open for too long, so in the meantime Alan was faster.

Mathcad is lousy at equations using vectors, so rewrite your system to just use the vector elements.

LT

Here is a selection of solutions (the argument ist C2 as Mathcad choses the last variable to be the free one)

You get a set of two solutions for every value of C2 and if you are only interested in real values, you may chose C2 in the range of approx. 0.79 to 2.21.

Obviously there are no more integer-only solutions than the four given in the pictures, two of them include a zero vector (either l or r).