That was a very incoherent answer ..

Couple of this before running the suite
question for you : is that a GUI script or VU script for Robot ?

- check whether your robot script can execute independently
- if yes,
- then what kind of selector have you used in the test suite
- does these test cases have dependency
- have you tried putting delay
- how many agent machine you have, have you check the resource utililization

possible solution ;
- try creating various suite by distributing the test cases to locate the problem
- try running these suites from different machine by deploying test manager agent


let me knoe if this help