diff --git a/README.md b/README.md
index 41804b9..0c2e75b 100644
--- a/README.md
+++ b/README.md
@@ -452,7 +452,8 @@ Output file:
 
 ### Convert from Caliscope, AniPose, FreeMocap, Qualisys, Optitrack, Vicon, OpenCap, EasyMocap, or bioCV
 
-If you already have a calibration file, set `calibration_type` type to `convert` in your [Config.toml](https://github.com/perfanalytics/pose2sim/blob/main/Pose2Sim/Empty_project/User/Config.toml) file.
+If you already have a calibration file, set `calibration_type` type to `convert` in your [Config.toml](https://github.com/perfanalytics/pose2sim/blob/main/Pose2Sim/Empty_project/User/Config.toml) file.\
+***N.B.:** If the original calibration file does not provide any residual errors, they will be logged as NaN. This is not an error and can be ignored.*
 - **From [Caliscope](https://mprib.github.io/caliscope/), [AniPose](https://github.com/lambdaloop/anipose) or [FreeMocap](https://github.com/freemocap/freemocap):**  
   - Copy your `.toml` calibration file to the Pose2Sim `Calibration` folder.
   - Calibration can be skipped since these formats are natively supported by Pose2Sim.