gap in exp....

I am refused in reason of experience. that's all i know about my application because i did not get my documents yet since last four months. i submitted my one exp letter without stamp and without detail as they required. may be it can be reason. and its hard to take new letter from this company again. if i wont show this exp letter in my profile then one year gap will come in my profile ..my question is that
is there any problem if any gap come in experience...???
should i justify this gap or not?