You mentioned you already found the problem. One thing to remember, is that llParticleSystem and a few other functions I forgot, are stupidly anal about types. eg, they force the proper use of integers and floats, and likewise for strings and keys, even though these types are interchangeable in 95% of the other LSL functions
There's a jira for this:
[#SVC-185] llParticleSystem (and others) anal about types - Second Life Issues