Prescribing Error: "Item 900 Is Missing or Invalid"

When sending a prescription, you may see an error similar to:

Item 900 is missing or invalid — The value "…" is invalid according to its datatype.

The prescription is rejected and never reaches the pharmacy. The value shown in quotes is the exact entry that failed validation.

What this error means

The prescription is transmitted to the pharmacy as a structured message, and every field in that message has to match a strict format. If one entry does not, the message is rejected as a whole — so the error can be triggered by a single character in a single field.

The most common cause is a number written without a digit before the decimal point. Numeric fields require a leading zero, so an entry such as .5  is rejected while 0.5  is accepted. The same applies to .25 , .75 , and any other bare decimal.

Other formatting that can trigger it includes fraction characters (½ ), slashes used as fractions (1/2 ), and stray symbols pasted in from another document.

How to fix it

1. Read the value in the error message. It names the exact entry that failed, which is usually enough to find the field it came from.
2. Always write a leading zero. Enter 0.5 , not .5 .
3. Spell out fractions in the directions. Write "Take 0.5 tablet twice daily" rather than "Take ½ tab BID" or "Take 1/2 tab BID".
4. Check every field on the prescription, not just the one you were editing — Quantity, Days Supply, Dose/Strength, Refills, and any free-text Directions or Note to Pharmacy.
5. Retype rather than paste. Text copied from another program can carry hidden or special characters that are not visible on screen.
6. Re-create the prescription instead of editing it. If a prescription is already sitting in Pending Medications or in the Rx Errors queue with the invalid value, delete it and add it again from scratch. Editing in place can leave the original value behind.
7. Check your saved sigs and favorites. If you routinely reuse a direction line, open it and confirm it does not contain a bare decimal, a fraction, or an unusual character.

Are we fixing the root cause?

Yes. We have asked DoseSpot to accept these entries rather than rejecting the prescription, so that no workaround is needed. Until that change ships, please use the guidance above.