Negative Cronbach’s Alpha When Running a Reliability Analysis

Hi Talk Stats member.

I have a question about getting a negative Cronbach’s Alpha when running a reliability analysis in SPSS. Here is what I have:

I have a standardized exam taken by 19 participants/valid cases.

The exam was graded with the score range of 1 - 4, including the decimals points in between (Ex. 2.75, 3, 3.3, 4) by 2 separate examiners.

Is the negative Cronbach's Alpha a result of having too few people in my sample (19) relative to the number of items in my scale ( range of 1-5 including the decimals in between/too many variations)?

I don't think the negative Cronbach Alpha is a result of a coding error in this case because the score is in scale measure.

Your help is greatly appreciated!