Workspace must contain histogram data

Could anyone explain what is meant by ’ workspace must contain histogram data’ when I try to convert Units from Q to TOF. I can load and plot the data in the workspace. Also the workspace has 1 histogram and 1752 bins. I generally work with two columns data and the histogram idea is not clear to me, could you please advice.

Many thanks

Mantid was originally developed for TOF instruments. Certain assumptions were made when ConvertUnits was written, such as the workspace has to be a histogram data. What you probably have is point data. What is the difference? In point data you have a Y value for every X value. In histogram data Mantid stores the bin boundaries. So you have one more X value than the number Y values. You can convert between the two representations using ConvertToHistogram and ConvertToPointData algorithms.